Year	Percent
1990	61.02
1991	61.09
1992	60.93
1993	61
1994	61.03
1995	60.95
1996	60.83
1997	60.73
1998	60.62
1999	60.59
2000	60.37
2001	60.28
2002	59.79
2003	59.61
2004	59.34
2005	59.19
2006	59.17
2007	59.09
2008	58.98
2009	58.8
2010	58.61
2011	58.58
2012	56.8
2013	54.96
2014	49.74
2015	44.5
2016	39.37
2017	39.7
2018	40.05
2019	40.44