Year	Percent
1983	15.9593
1984	20.757
1985	22.884
1986	21.5062
1987	19.9667
1988	19.1193
1989	16.1516
1990	16.8261
1991	17.0069
1992	18.592
1993	23.5055
1994	27.1805
1995	23.6676
1996	25.0269
1997	26.9627
1998	24.142
1999	24.739
2000	19.0014
2001	16.0051
2002	17.4748
2003	16.4892
2004	19.7488
2005	19.4601
2006	20.3559
2007	18.3135
2008	18.5326
2009	24.0349
2010	22.1644
2011	21.3548
2012	24.0859
2013	23.7846
2014	25.1133
2015	25.7797
2016	25.0675
2017	23.1413