Year	Percent
1990	12.44002
1991	13.81577
1992	19.94789
1993	18.48203
1994	19.13442
1995	21.74869
1996	23.03985
1997	24.63108
1998	23.65034
1999	18.70628
2000	18.92766
2001	19.56042
2002	18.48385
2003	20.72667
2004	20.2797
2005	18.52962
2006	16.38377
2007	17.19431
2008	15.4159
2009	13.54482
2010	11.66107
2011	5.50052
2012	8.70429
2013	8.10578
2014	7.83241
2015	1.84942
2016	1.70162