Year	Percent
1990	32.46
1991	32.69
1992	32.88
1993	32.99
1994	31.82
1995	32.09
1996	32.27
1997	33.29
1998	34.29
1999	35.3
2000	32.63
2001	38.36
2002	40.03
2003	41.74
2004	43.49
2005	42.49
2006	41.58
2007	40.71
2008	41.74
2009	43
2010	46.58
2011	50.71
2012	46.85
2013	42.97
2014	40.8
2015	35.84
2016	45.75
2017	43.04
2018	43.14
2019	43.22