Year	% female
1971	28.29224
1972	29.40691
1973	31.10489
1974	31.84028
1975	33.02334
1976	33.62559
1977	34.29436
1978	35.69271
1979	36.96297
1980	37.88961
1981	38.53421
1982	39.44699
1984	40.61467
1985	41.01321
1986	41.54406
1987	41.41816
1988	41.64793
1989	42.13226
1990	42.61915
1991	43.36117
1992	43.97733
1993	44.5727
1994	45.32277
1995	45.98217
1996	46.42445
1997	47.87854
1999	49.3134
2000	50.18435
2001	50.5497
2002	50.52748
2003	51.05841
2004	51.12901
2005	51.23837
2006	51.21634
2007	50.96425
2008	49.98504
2009	49.31622
2010	49.92082
2011	49.96174