IPv4 Allocation stats

We're not ARIN members so I can't post to arin-discuss - thought someone
here might be able to help me out....

Can anyone explain to me why the ARIN IPv4 Issued statistics, e.g.
http://www.arin.net/statistics/index.html#ipv4issued2003, do not seem to
match up with the stats available from

For example, if you add all the allocations and assignments listed in
arin.20030601 for April 2003 you get 819,456. Dividing by 256 to get /24
equivalents gives 3,201. But
http://www.arin.net/statistics/index.html#ipv4issued2003 states 7,056 /24
equivalents were issued in April 2003.

I'm sure there's a simple explanation. So what is it? Maybe I can't do

-- Mat