Year	Percent
1990	75.28
1991	76
1992	77.8
1993	78.08
1994	80.23
1995	81.27
1996	80.93
1997	82.29
1998	81.81
1999	80.48
2000	80.1
2001	79.8
2002	79.86
2003	79.64
2004	79.25
2005	78.17
2006	77.31
2007	76.48
2008	75.47
2009	75.11
2010	74.58
2011	73.79
2012	73.29
2013	72.89
2014	72.55
2015	72.39
2016	72.26
2017	72.16
2018	72.09
2019	72.05