Year	Percent
1990	72.11
1991	72.01
1992	72
1993	71.93
1994	71.86
1995	71.79
1996	71.82
1997	71.83
1998	71.81
1999	71.8
2000	71.84
2001	71.87
2002	71.99
2003	72.06
2004	72.19
2005	72.26
2006	72.43
2007	72.58
2008	72.7
2009	72.78
2010	72.84
2011	72.96
2012	73.07
2013	73.11
2014	73.07
2015	73.05
2016	72.34
2017	71.58
2018	71.47
2019	71.33