Year	Percent
1990	74.05
1991	73.51
1992	72.64
1993	71.44
1994	71.16
1995	71.68
1996	71.28
1997	71.86
1998	72.43
1999	72.53
2000	73
2001	71.07
2002	69.06
2003	66.96
2004	64.75
2005	62.44
2006	60.04
2007	57.56
2008	55.02
2009	52.41
2010	49.76
2011	49.82
2012	49.68
2013	49.57
2014	48.97
2015	48.58
2016	48.48
2017	48.41
2018	48.59
2019	48.42