Year	Percent
1990	31.12156
1991	30.76495
1992	25.46903
1993	31.54736
1994	26.11719
1995	22.41573
1996	23.89163
1997	21.84607
1998	20.88369
1999	14.58109
2000	13.72309
2001	16.63275
2002	34.09196
2003	33.29566
2004	32.37337
2005	27.14405
2006	28.29968
2007	29.52514
2008	28.98195
2009	42.82206
2010	42.09748
2011	44.79154
2012	39.74637
2013	64.82797
2014	91.88329
2015	70.6441