Year	Percent
1990	45
1991	45.59
1992	46.07
1993	46.48
1994	45.92
1995	45.33
1996	44.77
1997	44.17
1998	43.56
1999	42.92
2000	42.27
2001	41.61
2002	40.95
2003	40.26
2004	39.56
2005	38.86
2006	38.15
2007	37.42
2008	36.69
2009	35.95
2010	35.2
2011	34.46
2012	33.71
2013	33.62
2014	33.65
2015	33.5
2016	33.48
2017	33.35
2018	33.15
2019	32.95