Year	Percent
1976	10.13058
1977	10.31216
1978	11.90937
1979	15.81285
1980	18.97926
1981	25.35591
1983	29.04618
1985	29.91711
1986	32.23259
1987	32.99987
1988	38.44258
1989	34.22319
1990	28.80214
1991	32.3879
1992	31.20255
1993	32.61692
1994	32.15432
1995	33.02717
1996	33.7688
1997	37.99804
1998	43.32989
1999	44.5213
2001	44.75858
2002	42.39722
2005	42.35222
2006	43.37575
2007	54.64205
2009	66.93709
2012	67.97307
2013	70.08631
2014	67.29286
2015	68.054
2016	59.26494