Year	Percent
1990	52.32
1991	52.13
1992	51.85
1993	51.51
1994	51.11
1995	50.66
1996	50.87
1997	51
1998	51.07
1999	51.04
2000	51.51
2001	52.1
2002	52.73
2003	53.39
2004	54.08
2005	54.78
2006	55.44
2007	56.09
2008	56.7
2009	56.64
2010	56.38
2011	55.81
2012	54.73
2013	53.31
2014	51.83
2015	50.53
2016	48.95
2017	47.8
2018	47.05
2019	46.66