Year	Percent
1990	60.11
1991	61.7
1992	62.68
1993	62.24
1994	62.26
1995	60.28
1996	61.05
1997	61.3
1998	61.64
1999	62.75
2000	64.25
2001	63.86
2002	65.09
2003	64.31
2004	65.59
2005	66.47
2006	66.94
2007	66.45
2008	66.27
2009	68.33
2010	67.96
2011	67.69
2012	69.05
2013	69.27
2014	70.08
2015	70.66
2016	69.61
2017	70
2018	70.77
2019	71.66