Year	Percent
1990	69.88
1991	70.24
1992	69.59
1993	69.21
1994	69.22
1995	69.49
1996	69.36
1997	69.36
1998	69.49
1999	69.6
2000	69.74
2001	69.92
2002	70.54
2003	70.33
2004	70.38
2005	70.17
2006	70.09
2007	70.19
2008	69.67
2009	69.55
2010	68.37
2011	69.11
2012	69.75
2013	70.84
2014	70.91
2015	71.37
2016	71.6
2017	71.96
2018	72.26
2019	72.27