Year	Percent
1990	58
1991	58.47
1992	59.1
1993	59.5
1994	59.84
1995	60.36
1996	60.79
1997	61.21
1998	61.41
1999	61.59
2000	61.02
2001	60.36
2002	60.07
2003	60.71
2004	61.63
2005	62.29
2006	63.07
2007	63.83
2008	65.54
2009	65.5
2010	65.99
2011	67.19
2012	67.27
2013	67.47
2014	67.81
2015	68.07
2016	68.04
2017	68.52
2018	68.96
2019	68.9