http://jobs.aol.com/articles/2011/06/16/why-women-make-better-cops-doctors-and-world-leaders/?icid=maing-grid7%7Cmain5%7Cdl8%7Csec1_lnk3%7C71183
Most of those results seem to come from surveys... just because gender stereotypes are "happy" doesn't make them anything other than stereotypes.