Year	Years
1990	55.6
1991	55.1
1992	54.7
1993	54
1994	53.3
1995	52.8
1996	52.3
1997	48.3
1998	50.6
1999	51.9
2000	52.6
2001	53.1
2002	53.6
2003	54.5
2004	55.4
2005	56.1
2006	57.2
2007	57.9
2008	58.6
2009	59.6
2010	60.3
2011	60.8
2012	61.3
2013	61.5