Year	Percent
1990	38.22
1991	40.04
1992	40
1993	40.25
1994	39.58
1995	39.47
1996	39.42
1997	39.08
1998	38.89
1999	38.24
2000	37.88
2001	38.17
2003	51.51
2004	51.32
2005	51.43
2006	51.54
2007	49.83
2008	52.2
2009	52.71
2012	51.52
2014	50.29