Year	Percent
1990	53.13
1991	53.56
1992	54.64
1993	55.61
1994	57.22
1995	57.87
1996	58.5
1997	58.01
1998	58.85
1999	59.19
2000	58.7
2001	57.68
2002	56.5
2003	55.59
2004	54.71
2005	53.31
2006	51.93
2007	50.53
2008	49.09
2009	47.59
2010	46.65
2011	47.11
2012	45.4
2013	46.12
2014	45.66
2015	48.63
2016	47.22
2017	46.92
2018	43.72
2019	47.17