Year	Percent
1990	75.43
1991	76.22
1992	74.29
1993	72.06
1994	69.41
1995	69.32
1996	69.73
1997	69.18
1998	68.78
1999	68.9
2000	69.37
2001	70.2
2002	69.45
2003	69.86
2004	69.8
2005	69.02
2006	68.61
2007	68.29
2008	68.83
2009	68.43
2010	68.65
2011	68.77
2012	69.5
2013	69.9
2014	70.27
2015	70.95
2016	71.95
2017	72.2
2018	72.46
2019	72.72