I got interested by Bruce's plot of PG email traffic here
http://momjian.us/main/img/pgincoming.gif
and decided to try to extend it into the past. The data I have
available is just my own incoming mail log, but being a pack-rat by
nature I have that back to April 1998. Attached is a graph of Postgres
list messages per month since then. I should note that this covers only
the mail lists I'm subscribed to, which has been most of them since
about 1999; but the first few numbers in this chart are undercounts by
comparison. Also, the very last dot is month-to-date for November and
so is an underestimate.
So, to a first approximation, the PG list traffic has been constant
since 2000. Not the result I expected.
regards, tom lane