Oracle EBS Script to calculate number of requests run per week

SELECT COUNT(*) Total, 
sum(decode(greatest(0,ceil (sysdate - actual_completion_date)),
least(7,ceil(sysdate-actual_completion_date) ),1,0)) Week4, 
sum(decode(greatest(8,ceil (sysdate - actual_completion_date)), 

least(14,ceil(sysdate-actual_completion_date) ),1,0)) Week3,
sum(decode(greatest(15,ceil (sysdate - actual_completion_date)), 

least(21,ceil(sysdate-actual_completion_date) ),1,0)) Week2,
sum(decode(greatest(22,ceil (sysdate - actual_completion_date)), 

least(28,ceil(sysdate-actual_completion_date) ),1,0)) Week1
FROM FND_CONCURRENT_REQUESTS
WHERE ACTUAL_COMPLETION_DATE is not null;