Year	Percent
1986	14.93002
1987	16.25847
1988	17.08734
1989	17.18292
1990	24.52582
1991	22.38414
1992	21.22031
1993	21.69626
1994	20.9929
1995	21.39363
1996	20.78251
1997	21.00871
1998	19.20823
1999	19.84739
2000	20.47279
2001	16.4772
2002	14.53831
2003	21.61669
2004	20.72725
2005	19.53483
2006	24.5634
2007	23.41968
2008	26.2177
2009	21.30661
2010	20.3254
2011	24.05333
2012	26.02153
2013	23.49396
2014	23.40838
2015	23.50476
2016	51.8205
2017	36.11588