How To Calculate The Percentage Of Scheduled Hours

I have weekly wise scheduled hours of each employee and no of days scheduled for each employee,now i need to calculate no of employees scheduled less than 24 hours,no of emp's scheduled b/w 24 and 48 hrs and emp's scheduled more than 48 hrs in percentage for fisrt week,second week,3rd week and 4th week.

Like this

SCheduled Hrs 8/1/2010 8/8/2010 8/15/2010 8/22/2010

Less tha 24 hrs 5% 5% 5% 5%

b/w 24 and 48 hrs 4% 5% 5% 5%

>48 91% 90% 90% 90%