Year	Percent
1983	2.568
1984	3.0151
1985	3.0529
1986	3.8823
1987	4.0745
1988	4.1739
1989	4.571
1990	3.9428
1991	4.0752
1992	4.3551
1993	5.1065
1994	6.2225
1995	6.625
1996	6.858
1997	7.2353
1998	7.2755
1999	6.9417
2000	6.4156
2001	5.8828
2002	5.6736
2003	5.5264
2004	5.0904
2005	5.0527
2006	4.5091
2007	4.0334
2008	4.6737
2009	5.8376
2010	6.507
2011	6.5131
2012	8.576
2013	10.3314
2014	10.8207
2015	10.3837
2016	10.0906
2017	9.7393