Lisa Simone, a biomedical software engineer at FDA, published an article in the Biomedical Instrumentation & Technology Journal (Nov-Dec 2013) with information on an analysis of historical software related recalls using internal information at FDA as well as other sources. The article breaks down the recalls by year and product type. She investigated the years 2005-2011, and found 84 in 2005, 119 in 2006, 119 in 2007, 192 in 2008, 146 in 2009, 147 in 2010, and 315 in 2011. In 2011, there was an increase in all recalls, including software-related ones. From 2006-2011, the percentage of software related recalls (which includes where software was modified to fix other types of problems) ranged from 18-25%. Imaging and radiology software accounted for the largest number of software recalls.
SoftwareCPR scans public information on medical device software recalls and posts them, including annual totals. Our totals are different than this article (both show an increase in 2011), but as stated in the article even internally FDA has no good way of identifying software recalls, so numbers are imprecise.