Year	Percent
1990	49.72
1991	50.11
1992	50.47
1993	50.82
1994	51.17
1995	51.53
1996	51.03
1997	50.35
1998	49.55
1999	48.66
2000	47.7
2001	46.48
2002	45.22
2003	43.97
2004	42.79
2005	41.71
2006	41.31
2007	40.92
2008	40.54
2009	40.2
2010	41.22
2011	42.24
2012	36.19
2013	38.18
2014	40.32
2015	34.84
2016	34.95
2017	35.2
2018	35.57
2019	35.99