Year	Percent
1990	33.29497
1991	31.85663
1992	33.34604
1993	33.84067
1994	36.87173
1995	35.51369
1996	34.59456
1997	35.42771
1998	43.02659
1999	43.64113
2000	44.26417
2001	44.61362
2002	43.34338
2003	41.87251
2004	41.15393
2005	46.54864
2006	45.38472
2007	47.41237
2008	45.01234
2009	45.45139
2010	44.22587
2011	42.72757
2012	41.85394
2013	41.01599
2014	40.90123
2015	39.99219
2016	39.2123
2017	37.5033