Year	Percent
1976	34.89998
1977	27.77805
1978	42.53546
1979	23.01057
1980	38.03773
1981	45.84482
1982	50.17395
1983	69.89675
1984	63.61461
1985	60.32697
1986	83.13373
1987	74.53342
1988	44.50263
1989	36.42973
1990	37.13695
1991	33.77929
1992	27.67286
1993	31.11176
1994	25.29155
1995	30.31307
1996	39.44128
1997	44.17455
1998	51.80365
1999	74.28486
2000	64.28241
2001	49.5813
2002	16.59737
2003	38.29127
2004	29.67588
2005	19.72463
2006	31.51133
2007	12.11147
2008	11.00062
2009	21.17258
2010	18.64254
2011	15.65499
2012	13.75656
2013	16.82563
2014	19.69761
2015	24.6227
2016	34.9305