Year	Percent
1990	42.22
1991	42.2
1992	42.11
1993	42.13
1994	42.21
1995	42.17
1996	42.32
1997	42.07
1998	41.76
1999	41.64
2000	42.11
2001	38.34
2002	37.55
2003	40.44
2004	39.87
2005	40.23
2006	40.14
2007	41.28
2008	40.54
2009	40.58
2010	41.02
2011	42.37
2012	42.74
2013	42.98
2014	43.31
2015	45.48
2016	45.55
2017	46
2018	45.5
2019	46.33