Year	Percent
1990	58.49
1991	58.85
1992	59
1993	59.15
1994	59.52
1995	59.63
1996	60.06
1997	60.29
1998	60.67
1999	60.91
2000	61.1
2001	61.39
2002	60.83
2003	61.96
2004	62.44
2005	62.06
2006	61.83
2007	61.59
2008	61.36
2009	61.5
2010	61.62
2011	61.76
2012	61.21
2013	61.31
2014	60.61
2015	59.91
2016	59.19
2017	58.46
2018	58.58
2019	58.7