Year	Percent
1990	59.94
1991	60.13
1992	61.59
1993	63
1994	64.36
1995	65.73
1996	67.39
1997	69.02
1998	70.12
1999	71.56
2000	69.16
2001	72.42
2002	74.92
2003	75.5
2004	77.42
2005	75.04
2006	78.16
2007	80.66
2008	80.47
2009	81.03
2010	81.74
2011	81.41
2012	81.21
2013	80.83
2014	79.94
2015	78.68
2016	78.46
2017	80.28
2018	80.75
2019	81.04