Year	Percent
1990	59.48
1991	59.85
1992	60.4
1993	61.86
1994	36.51
1995	58.88
1996	56.41
1997	58.79
1998	60.34
1999	60.62
2000	62.81
2001	63.75
2002	35.49
2003	35.9
2004	34.67
2005	34.99
2006	36.25
2007	36.69
2008	37.21
2009	37.7
2010	37.6
2011	38.34
2012	39.38
2013	44.3
2014	44.9