Help! ssCpuRaw on multi-processor systems

Hi, I have a question about ssCpuRaw on machines with two or more
processors.  I measure the counters ssCpuRawUser and ssCpuRawSystem at five
minute intervals, and I think I should be able to get the percentages by
taking the difference from the last sample and dividing by 30,000 (the
number of ticks in 5 minutes):

 percentage user = (ssCpuRawUserNow - ssCpuRawUserThen) / 30000

But do I have to also divide by the number of CPUs?

I tried reading the source code, but that's even more confusing.  In
cpu_linux.c, it seems to return the total ticks across all CPUs (so I should
divide), but in vmstat_solaris2.c it seems to already divide by the number
of CPUs (so I shouldn't).

Can anyone help me?

Jen in Canada