Year	Years
1990	50.3
1991	50.7
1992	50.7
1993	49.6
1994	50.5
1995	50.9
1996	51
1997	51.2
1998	51.6
1999	51.9
2000	52.6
2001	53
2002	53.8
2003	54.5
2004	55.2
2005	56
2006	56.9
2007	57.6
2008	58.3
2009	58.9
2010	59.4
2011	59.7
2012	60.1
2013	60.4