As of March, outside spending on 2012 presidential elections had surpassed 2008 spending by 234%.
"In the 1992 election season, when it was entirely possible (under that 1976 Supreme Court decision) for Sheldon Adelson or George Soros to spend unlimited sums independently on elections, total outside spending up to March 8 was about $1.5 million. In 2000, total outside spending up to March 8 was $2.6 million. In 2004 and 2008, with the explosion of 527 organizations, total spending to March 8 was $14 million and $37.5 million. What is the total for this election season through March 8? More than $88 million, 234 percent of 2008's numbers and 628 percent of 2004's. If this was not caused by Citizens United, we have a mighty big coincidence on our hands.”
Richard L. Hasen, “The Numbers Don’t Lie,” New York Times, March 9, 2012. http://www.slate.com/articles/news_and_politics/politics/2012/03/the_sup....