Fannie Mae and Freddie Mac generated $182.2 billion of new single-family mortgage-backed securities during the final three months of 2013, their lowest quarterly output since the third quarter of 2011, according to a new Inside Mortgage Finance analysis and ranking. Fourth-quarter volume for the two government-sponsored enterprises was down 36.1 percent from the previous quarter, with Fannie posting the bigger decline, 36.8 percent. Freddie volume in the final three months of the year was off 34.7 percent from the third quarter, which helped modestly boost its share of the GSE market to 35.2 percent. For the year, Freddie accounted...[Includes three data charts]