Year	Percent
1986	3.6717
1987	4.0524
1988	5.8507
1989	7.4564
1990	8.384
1991	11.268
1992	11.393
1993	10.459
1994	8.782
1995	6.44
1996	6.324
1997	6.853
1998	7.804
1999	7.297
2000	6.256
2001	5.476
2002	5.125
2003	4.4409
2004	3.565
2005	3.514
2006	3.562
2007	3.396
2008	4.082
2009	6.101
2010	6.225
2011	6.251
2012	6.516
2013	5.629
2014	5.039
2015	4.9153
2016	4.763
2017	4.256