Year	Years
1990	46.9
1991	46.9
1992	46.8
1993	46.9
1994	46.7
1995	46.4
1996	46.3
1997	46.2
1998	46.3
1999	46.5
2000	46.7
2001	46.8
2002	47.3
2003	47.6
2004	48
2005	48.4
2006	49
2007	49.6
2008	50.3
2009	51.1
2010	51.7
2011	52.1
2012	52.3
2013	52.8