Try using sar instead.
sar -u
AIX naxxxx 1 5 0008F2XXXC00 08/11/05
00:00:01 %usr %sys %wio %idle
…
14:20:00 5 27 1 67
14:40:01 4 26 1 69
15:00:00 4 26 1 68
15:20:00 5 27 4 64
15:40:01 7 27 7 58
Average 5 26 1 68
Your system is probably storing the sar output for 30 days. Ours is stored in /var/adm/sa as saDD where DD is the day of the month. Your location may be different. If you find the archived sar files use ‘sar -f filename’ to view a specific file.
You can also get information from sar about your calls, kernel, paging, etc.
You could also use vmstat to get memory, paging, faults and cpu usage.
