Source:
http://en.wikipedia.org/wiki/Usenet
Over time, the amount of Usenet traffic has steadily increased.
It is important to note, however, that much of this traffic increase reflects not an increase in discrete users or newsgroup discussions, but instead the combination of massive automated spamming
and an increase in the use of .binaries newsgroups in which large files (frequently pornography or pirated media) are often posted publicly. A small sampling of the change (measured in feed size per day) follows: 3.12 TB 2007-04-21