Year	Percent
1983	2.2819
1984	2.0505
1985	2.2378
1986	1.926
1987	1.765
1988	1.5
1989	1.1576
1990	1.1869
1991	1.1283
1992	1.5813
1993	1.8706
1994	2.9969
1995	2.0909
1996	2.4824
1997	1.8478
1998	1.9056
1999	1.7784
2000	1.8207
2001	1.5621
2002	1.9344
2003	2.9558
2004	3.6826
2005	3.5038
2006	3.5475
2007	3.5516
2008	4.317
2009	4.3554
2010	3.7926
2011	3.8367
2012	4.527
2013	5.4201
2014	5.9213
2015	6.1047
2016	6.0098
2017	5.5411