Year	Percent
1983	11.6855
1984	12.0996
1985	11.7332
1986	11.5636
1987	11.3506
1988	12.4597
1989	12.3652
1990	11.7258
1991	12.8602
1992	12.8777
1993	13.6255
1994	13.664
1995	13.761
1996	15.4237
1997	14.8235
1998	16.686
1999	18.1898
2000	17.0348
2001	15.9028
2002	15.3376
2003	14.4628
2004	15.9596
2005	15.4305
2006	13.7576
2007	12.9056
2008	11.5125
2009	13.2828
2010	16.3347
2011	21.5126
2012	28.2102
2013	31.3468
2014	30.1672
2015	28.8525
2016	28.0958
2017	26.0684