Year	Years
1990	52.3
1991	52.7
1992	53
1993	53.5
1994	53.9
1995	54.3
1996	54.7
1997	54.9
1998	55
1999	55.4
2000	55.6
2001	56
2002	56.4
2003	56.8
2004	57.1
2005	57.3
2006	57.6
2007	58
2008	58.3
2009	58.7
2010	59.1
2011	59.5
2012	59.9
2013	60.2