Year	Percent
1986	7.9324
1987	8.6722
1988	12
1989	14.6125
1990	15.358
1991	21.283
1992	21.176
1993	19.217
1994	16.072
1995	12.353
1996	12.882
1997	13.817
1998	16.033
1999	15.227
2000	14.541
2001	12.309
2002	11.793
2003	10.3287
2004	8.949
2005	9.362
2006	9.477
2007	10.035
2008	11.827
2009	16.194
2010	17.062
2011	18.524
2012	17.626
2013	15.891
2014	14.335
2015	13.7179
2016	13.059
2017	12.379