Year	Percent
1983	30.62518
1984	35.12067
1985	34.67102
1986	33.22019
1987	38.31988
1988	33.69919
1989	23.67129
1990	24.8448
1991	28.64312
1992	24.31105
1993	21.45483
1994	38.04789
1995	39.65251
1996	41.54352
1997	41.47185
1998	44.84583
1999	47.50251
2000	48.95953
2001	49.09935
2002	49.72434
2003	49.72059
2004	48.80993
2005	48.95761
2006	47.51548
2007	47.45468
2008	49.02983
2009	51.5546
2010	52.80659
2011	50.38686
2012	53.19429
2013	53.0893
2014	53.51249
2015	56.22041
2016	54.18245
2017	52.74505