Year	% female
1971	8.10544
1972	9.05844
1974	11.37677
1985	15.16503
1987	15.01739
1988	15.28255
1989	15.60901
1990	17.80059
1991	15.75086
1994	17.46389
1995	18.73085
1996	19.37403
1997	19.98639
1998	20.32204
1999	20.45087
2000	21.86565
2001	23.10012
2002	24.69454
2003	24.04427
2004	24.52762
2005	25.3572
2006	26.0767
2007	30.58231
2008	28.74376
2009	28.88066
2010	29.38008
2011	30.09662
2012	31.00787
2013	31.13918
2014	30.7398
2015	30.72509
2016	31.18309