Year	Percent
1990	45.04
1991	45.24
1992	45.22
1993	45.17
1994	45.34
1995	45.32
1996	45.26
1997	43.63
1998	44.53
1999	43.58
2000	42.61
2001	41.65
2002	40.67
2003	39.67
2004	42.07
2005	42.2
2006	43.23
2007	41.34
2008	40.81
2009	38.63
2010	36.52
2011	36.86
2012	37.19
2013	36.17
2014	36.36
2015	39.89
2016	42.27
2017	42.09
2018	40.89
2019	40.29