Last week, National Public Radio aired a story on my Pharma Wars series, which chronicles an epic battle between men who ran two competing cybercrime empires that used spam to pimp online pharmacy sites. As I was working with the NPR reporter on the story, I was struck by how much spam has decreased over the past couple of years. Below is a graphic that’s based on spam data collected by Symantec’s MessageLabs. It shows that global spam volumes fell and spiked fairly regularly, from highs of 6 trillion messages sent per month to just below 1 trillion. I produced this graph based on Symantec’s raw spam data.