Toyota (and most manufacturers) release sales numbers by the month. Wikipedia will tell you everything as well as a quick google.
over a billion served . . . oh wait thats mcdonalds a survey company announced recently that your average Volt owner is in electric mode 70% of the time, and they were able to extrapolate how many millions of gallons the 7000 volt owners combined have saved, so instead of asking how many prius sold we should be more interested in finding out how many gallons of fuel all the Prius owners combined have saved over driving a conventional economy car. I'd be interested in seeing estimates for US, north america and the world.
Actually over 3 million Prius have been sold. From Wikipedia: The Prius first went on sale in Japan in 1997, making it the first mass-produced hybrid vehicle. It was subsequently introduced worldwide in 2001. The Prius is sold in more than 70 countries and regions, with its largest markets being those of Japan and North America.[2] In May 2008, global cumulative Prius sales reached the milestone 1 million vehicle mark,[3] and in March 2011, the Prius reached worldwide cumulative sales of 3 million units.[4] The U.S. is the largest market, with 1 million Priuses sold by early April 2011,[5] and Japan reached the 1 million mark in August 2011.[6] Since its launch in 2009, the third-generation model has sold more than 1 million units worldwide by September 2011.[7] Scroll down to the bottom of the article for more sales details: [ame=http://en.wikipedia.org/wiki/Toyota_Prius]Toyota Prius - Wikipedia, the free encyclopedia[/ame]