Those figures don't count the thousands of masters who only race in masters races.
Also, I know a lot of guys who only do road races and others who only do crits.
Here are the numbers on licenced cyclists in the Nor Cal/Nevada association.
USCF riders in the NCNCA region (as of June 8th, 2007)
Total USCF Members 3573 Cat Total under 35 35+ 45+ 55+
Cat 5 939 348 591 268 64
Cat 4 men 1032 303 729 297 63
Cat 4 women 285 131 154 68 13
Cat 3 men 659 172 487 191 49
Cat 3 women 124 56 68 31 7
Cat 2 men 328 104 224 89 20
Cat 2 women 74 32 42 14 0
Cat 1 men 100 38 62 14 0
Cat 1 women 32 15 17 3 0
Juniors total 202
Junior Men 175
Junior Women 27
Sorry, the chart doesn't line up well, but you get the idea.
Here's a link.
http://www.ncnca.org/docs/demographics.shtml