Year	Years
1990	56.4
1991	56.7
1992	56.9
1993	57.1
1994	57.4
1995	57.9
1996	58.4
1997	59
1998	59.5
1999	60
2000	60.5
2001	60.9
2002	61.2
2003	61.5
2004	61.8
2005	62.3
2006	62.7
2007	63.1
2008	63.4
2009	63.6
2010	63.8
2011	63.9
2012	64.1
2013	64.3