Thaks for your reply Mohit.

PFA below is my code Can you please do some changes which need to so that i can change it accordingly to work it properly.

In debug log its showing the exception in Red coloured line.Please help.

public class planthourExtension {
private final Get_Hour_Report__cplant;
public String year;
public String previousYear;
public Integer intYear = 0;
public Integer intPreviousYear = 0;
public String reporttype;
public String reportperiod;
public String reportCategory;
public String facility;
public String country;
public String plantDivision;
List<Decimal> cumulativemanhr=new List<Decimal>();
List<Decimal> cummanhr1 = new List<Decimal>();
List<Decimal> avgemployee = new List<Decimal>();
Decimal **bleep** = 0;
decimal hr = 0;
List<Monthly_home_Hour__c> incidentrec = new list<Monthly_home_Hour__c>(); 
public string firstWhereClause = '';
public string secondWhereClause = '';
public string secondWhereClause1 = '';
public List<string> mon = new List<String>();

public planthourExtension(ApexPages.StandardController controller) {

this.plant = (Plant_Hours_Report__c)controller.getRecord();
Get_Hour_Report__co = [Select Country__c,Division_div__c,Facility__c, Reporting_Category__c,
Report_Year__c,Report_Type__c,Reporting_Period__c
From Get_Hour_Report__cWhere Id =: plant.Id];

year= o.Report_Year__c;
if(year!= null){
intYear = Integer.valueof(year);
intPreviousYear = intYear - 1;
previousYear = String.valueof(intPreviousYear);
}
reporttype=o.Report_Type__c;
reportperiod=o.Reporting_Period__c;
facility = o.Facility__c;
reportCategory = o.Reporting_Category__c;
plantDivision = o.Division_div__c;
country = o.Country__c;
system.debug('reporttype is '+reporttype);

if(reporttype == 'Facility'){
firstWhereClause = 'Facility__c = \''+facility+'\' and Reporting_Category__c =\''+reportCategory+'\'';
}else if(reporttype == 'Sub'){
firstWhereClause = ' Country__c = \''+country+'\' and Reporting_Category__c =\''+reportCategory+'\'';
}else if(reporttype == 'Division'){
firstWhereClause = ' Country__c = \''+country+'\' and Division__c = \''+plantDivision+'\'';
}else {
firstWhereClause = ' Country__c = \''+country+'\'';
}

Date currentDate = date.today();

Integer currentMonth = currentDate.month();
system.debug('Current Month is'+currentMonth );

String[] monthQuery = new String[]{};
String[] monthQuery1 = new String[]{};

if(reportperiod == 'Calendar'){
system.debug('Entered Calendar');
for(Integer i=1;i<=currentMonth;i++ ){
monthQuery.add('\''+String.valueof(i)+'\'');
}
system.debug('monthQuery is '+monthQuery);
secondWhereClause = ' and Reporting_Year__c =\''+year+'\' and Reporting_Month__c in '+monthQuery+'';

}else if(reportperiod == 'Fiscal'){
system.debug('Entered Fiscal');
if(currentMonth >= 10){
for(Integer i=10;i<=currentMonth;i++ ){
monthQuery.add('\''+String.valueof(i)+'\'');
}
}else{
for(Integer i=1;i<=currentMonth;i++ ){
monthQuery.add('\''+String.valueof(i)+'\'');
}
for(Integer i=10;i<=12;i++ ){
monthQuery1.add('\''+String.valueof(i)+'\'');
}
}
secondWhereClause = ' and Reporting_Year__c =\''+year+'\' and Reporting_Month__c in '+monthQuery+'';
secondWhereClause1 = ' and Reporting_Year__c =\''+previousYear+'\' and Reporting_Month__c in '+monthQuery1+'';

}else if(reportperiod == 'Rolling'){
system.debug('Entered Rolling');
for(Integer i=1;i<currentMonth;i++ ){
monthQuery.add('\''+String.valueof(i)+'\'');
}
for(Integer i=currentMonth;i<=12;i++ ){
monthQuery1.add('\''+String.valueof(i)+'\'');
}

secondWhereClause = ' and Reporting_Year__c =\''+year+'\' and Reporting_Month__c in '+monthQuery+' ';
secondWhereClause1 = ' and Reporting_Year__c =\''+previousYear+'\' and Reporting_Month__c in '+monthQuery1+'';
}

} 


public List<Monthly_home_Hour__c> getManhour() {

List<Monthly_home_Hour__c> finalmph = new List<Monthly_home_Hour__c>();


if(!secondWhereClause1.equals('')){

List<Monthly_home_Hour__c> mph1= Database.query('SELECT Name,Month__c,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause+ ' ' + secondWhereClause1 + ' order by Reporting_Month__c ');

for(Integer i=0; i<mph1.size();i++){
finalmph.add(mph1[i]);
} 
} 
List<Monthly_home_Hour__c> mph= Database.query('SELECT Name,Month__c,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause + ' ' +secondWhereClause + ' order by Reporting_Month__c ');

for(Integer i=0; i<mph.size();i++){
finalmph.add(mph[i]);
}

return finalmph;
}

public List<Decimal> getCumulativeManhour() {

Decimal cummanhr = 0;
Decimal cummanhrcum = 0;

if(!secondWhereClause1.equals('')){

List<Monthly_home_Hour__c> mph1= Database.query('SELECT Name,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause+ ' ' + secondWhereClause1 + ' order by Reporting_Month__c ');

if(mph1.size()>0){
for(Integer i=0;i<mph1.size();i++)
{
cummanhr =mph1[i].Man_hours__c;
cummanhrcum = cummanhrcum + cummanhr;
cummanhr1.add(cummanhrcum);
}
}
} 
List<Monthly_home_Hour__c> mph= Database.query('SELECT Name,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause + ' ' +secondWhereClause + ' order by Reporting_Month__c ');

if(mph.size()>0){
for(Integer i=0;i<mph.size();i++)
{
cummanhr =mph[i].Man_hours__c;
cummanhrcum = cummanhrcum + cummanhr;
cummanhr1.add(cummanhrcum);
}
} 
return cummanhr1;
}
public List<Decimal> getAverageEmployee() {
Integer i= 0;
Integer j= 0;
Decimal avgemp = 0;
Decimal avgemployeeset = 0;

if(!secondWhereClause1.equals('')){

List<Monthly_home_Hour__c> mph1= Database.query('SELECT Name,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause+ ' ' + secondWhereClause1 + ' order by Reporting_Month__c ');

if(mph1.size()>0){

avgemployeeset = 0;
for(i=0;i<mph1.size();i++)
{
avgemp =mph1[i].Employee__c;

avgemployeeset = ((avgemployeeset*i) + avgemp)/(i+1);

avgemployee.add(avgemployeeset);
j = i+1;
}
}
} 
List<Monthly_home_Hour__c> mph= Database.query('SELECT Name,Reporting_Month__c,Employee__c,Man_hours__c,'
+'Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause + ' ' +secondWhereClause + ' order by Reporting_Month__c ');

if(mph.size()>0){
for(Integer m=0;m<mph.size();m++)
{
avgemp =mph[m].Employee__c;

avgemployeeset = ((avgemployeeset*j) + avgemp)/(j+1);

avgemployee.add(avgemployeeset);
j++;
}
}

return avgemployee;
}


public List<Monthly_home_Hour__c> getCumulativeRolling() {

List<Monthly_home_Hour__c> finalmph = new List<Monthly_home_Hour__c>();

if(!secondWhereClause1.equals('')){
List<Monthly_home_Hour__c> mph1= Database.query('SELECT Name,Month__c,Reporting_Month__c,Incidents__c,Total_Recordable_Rate__c,'
+' Lost_Work_Incidents__c,Lost_Work_Rate__c,Days_Away_From_work__c,'
+' Days_Away_From_Work_Rate__c,Medical_Treatment__c, '
+' Medical_Treatment_Rate__c,Fatalities__c,'
+' Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause+ ' ' + secondWhereClause1 + ' order by Reporting_Month__c ');

for(Integer i=0; i<mph1.size();i++){
finalmph.add(mph1[i]);
}

}
List<Monthly_home_Hour__c> mph= Database.query('SELECT Name,Month__c,Reporting_Month__c,Incidents__c,Total_Recordable_Rate__c,'
+' Lost_Work_Incidents__c,Lost_Work_Rate__c,Days_Away_From_work__c,'
+' Days_Away_From_Work_Rate__c,Medical_Treatment__c, '
+' Medical_Treatment_Rate__c,Fatalities__c,'
+' Reporting_Year__c FROM Monthly_home_Hour__c '
+'where '+ firstWhereClause+ ' ' + secondWhereClause + ' order by Reporting_Month__c ');

for(Integer i=0; i<mph.size();i++){
finalmph.add(mph[i]);
}
return finalmph;
}
}

Thanks in advance:)))