Year	Percent
1983	33.14063
1984	34.41216
1985	35.94758
1986	36.22611
1987	35.83283
1988	34.20051
1989	33.67017
1990	34.64244
1991	35.54866
1992	32.78218
1993	29.66444
1994	27.9966
1995	28.91899
1996	28.5455
1997	23.2747
1998	23.1849
1999	23.10374
2000	21.83558
2001	21.7438
2002	21.65936
2003	22.92839
2004	22.24734
2005	23.77534
2006	22.89652
2007	23.64405
2008	22.76735
2009	24.07941
2010	24.52886
2011	22.70512
2012	22.86223
2013	23.66924
2014	24.70064
2015	25.44176
2016	25.53928
2017	24.28173