crash risk sas code

[Rym Mabrouk]

Hello, 

I am trynig to run a sas code to calculate stock price crash risk. i use daily data to calculate  the weekly return. then I need to include as control variable deturn  defined as  The average monthly share turnover over fiscal year t minus the average monthly share turnover over fiscal year t−1. The monthly share turnover is calculated as the trading volume over the month scaled by the total number of shares outstanding at the end of the month.   

can any one please help me about the sas code how to do so ?