Just an aside (since I just have the data handy), as of a few weeks
ago, the InterNIC data base had the following prefix counts for their
network number entries:
PREFIX FREQUENCY
========== =========
-536870912 1
3 2
7 1
8 78
9 12
10 22
11 23
12 39
13 50
14 81
15 47
16 9057
17 260
18 583
19 1066
20 1870
21 2197
22 2335
23 2721
24 64386
31 86
I sure am liking those 31 bit masks.