This Seattle Times article says the Washington state legislature is one of only a few state legislatures in which the number of women and racial minorities declined in the 2012 election. The article quotes an official of the state League of Women Voters as saying one reason for the decline is that women are less likely to run for office when campaigns are so personally unpleasant and when so much campaign rhetoric is hostile.
Washington state started using the top-two system starting in 2008. Some supporters of top-two argue that top-two systems bring about more moderation and less polarization, but political scientists who have studied the Washington state legislature dispute those generalizations.
Nations that use proportional representation have the highest percentage of females in national legislatures. Proportional representation systems generally give political parties great influence over who gets nominated, and in most proportional representation systems, parties leaders make determined efforts to increase female representation.