proc expand to calculate moving avg exlcuding current data point

[a_khedekar]

I am using proc expand to calculate moving average for 12 weeks of data. But my requirement is to calculate moving average for 12 weeks (excluding current week) and compare that with current week. Is there any way to achieve that using proc expand? 

Basically I want to calculate moving avg for 12 weeks excluding current week.

proc expand data=alerttable out=base_y method=none factor=(1:11);
   id weekstart;
   by strategynm;
   convert weekcount=MovAv30  / transformout=(movave 12);
   convert weekcount=CurrVal  / transformout=(movave 01);
   convert weekcount=Std      / transformout=(movstd 12); 
   convert weekcount=PreVal	  / transformout=(lag 1);
   convert weekcount=pctdiff  / transformout=(PCTDIF);
run;

Thanks

[unison]

Do you have daily observations? Weekly? To better assist, please provide sample data in a data step.

[a_khedekar]

Observations are weekly with weekcount for each week.