National Public Radio's ombudsman has released a report headlined "Where Are The Women?".

Elsewhere, it seems. 

The article, published April 2, 2010, examines 104 shows between April 13, 2009 and January 9, 2010, and documents 2,502 male sources and 877 female sources, a discrepancy of 74% to 26%.

This is a slight improvement over previous studies: in 1991, Fairness and Accuracy in Reporting (FAIR) found the female source rate to be 19%. In 2003, the same organization reported it at 21%.

Read the full report here.