Year	Percent
1980	32.74336
1981	33.33333
1982	35.38462
1983	34.09091
1984	33.33333
1985	36.87943
1986	34.30657
1987	35.21127
1988	34.69388
1989	36.11111
1990	31.33333
1991	34.375
1992	23.65952
1993	21.78583
1994	10.07277
1995	15.58786
1996	23.04362
1997	22.22149
1998	21.7977
1999	21.22938
2000	20.99802
2001	20.53604
2002	22.73694
2003	24.08493
2004	24.1763
2005	23.75851
2006	21.71414
2007	20.90052
2008	18.94396
2009	18.92652
2010	19.31634
2011	20.50983
2012	21.07267
2013	20.87833
2014	20.63855
2015	21.32922
2016	21.45031
2017	22.06169