According to a recent report by Symantec, a whopping 87.4% of this year's email messages were spam. That figure peaked in May, with spam accounting for 95% of all emails in the month. At its lowest, spam emails accounted for 73.8% of emails in early 2009 after the US ISP McColo was shut down in late 2008.
Celebrity spam attacks surged, thanks in part to the numerous high-profile deaths this year including Patrick Swayze, Natasha Richardson, and most of all, Michael Jackson. At its height, Jackson-related spam made up nearly 2% of all spam messages.
Symantec noted that image spam reemerged at levels not observed since early 2007, accounting for 22% of all spam email. Other 2009 highlights include an uptick in malicious attachments and the continued migration of spam to new mediums like blogs and social networks.
Symantec believes 2010 will be an active year for spammers, with botnets playing a significant role in distributing the junk. You can read the company's 17-page report here for a complete look at recent spam trends.