Year	Percent
1990	73.62
1991	73.05
1992	72.87
1993	72.65
1994	73.28
1995	74.04
1996	74.12
1997	73.72
1998	73.65
1999	73.49
2000	73.95
2001	74.21
2002	74.3
2003	74.61
2004	74.47
2005	75.48
2006	75.84
2007	76.23
2008	76.53
2009	76.37
2010	76.45
2011	76.65
2012	76.41
2013	76.4
2014	76.34
2015	77.01
2016	77.02
2017	77.51
2018	78.07
2019	78.51