Despite the ups and downs of the general markets and a U.S. government shutdown at the beginning of the year that contributed to no biopharma companies graduating to the public ranks in January, the enthusiasm for biopharma IPOs has remained steady since then.

Drugs for rare diseases now account for 31% of R&D pipelines, up from 18% in 2010 and just 11% in 2005, according to a report from the Tufts Center for the Study of Drug Development. That's currently nearly 3,500 drugs in development, more than double the 1,530 in 2010.