Blog spam marketing trends | 博客垃圾邮件营销的发展趋势

I was doing an upgrade on the on the WordPress software and thankfully everything went ok. Whilst I was poking around the new interface, I checked in the Akismet spam blocker statistics for the first time in ages.
akismet blog spam stats 2008 - 2011
Now this isn’t scientific, but it looks like blog spam was most prolific in 2009 and has declined since (who knows it may get a renaissance in 2012, but I hope not). Is this because there are easier pickings on social platforms like Twitter now? Has anybody else found a similar pattern?