Year	Percent
1990	37.45463
1991	33.63915
1992	39.35358
1993	47.70761
1994	43.62497
1995	41.5077
1996	31.94351
1997	25.68952
1998	25.0199
1999	22.85433
2000	20.12594
2001	21.28369
2002	19.84033
2003	22.81102
2004	26.06581
2005	22.16805
2006	25.00539
2007	31.68441
2008	30.78911
2009	26.278
2010	29.12998
2011	36.03874
2012	33.11177
2013	31.06943
2014	29.78834
2015	24.77675
2016	22.73874