Can someone explain this to me?

How can mysql use 44% CPU while the CPU is 98.8 percent idle? Okay, this is quite an extreme difference. I've been watching a small webserver (266mhz, FreeBSD 4.7) and there always seems to be a difference between the idle CPU cycles and the (combined) CPU cycles that all the processes use.

Code:
CPU states:  0.4% user,  0.0% nice,  0.0% system,  0.8% interrupt, 98.8% idle
Mem: 33M Active, 9712K Inact, 26M Wired, 5752K Cache, 17M Buf, 488K Free
Swap: 300M Total, 10M Used, 290M Free, 3% Inuse

  PID USERNAME PRI NICE  SIZE    RES STATE    TIME   WCPU    CPU COMMAND
  149 mysql      2   0 34292K  7640K poll    22.3H 44.09% 44.09% mysqld
46560 www        2   0  5160K  4336K sbwait   0:09  1.32%  1.32% httpd
46561 www        2   0  5024K  4212K sbwait   0:05  0.78%  0.78% httpd
46565 www        2   0  5080K  4244K sbwait   0:07  0.73%  0.73% httpd