Year	Years
1990	51.4
1991	53.4
1992	51.6
1993	52.1
1994	51.1
1995	52.1
1996	51.7
1997	54.1
1998	54.5
1999	55.1
2000	55.9
2001	56.5
2002	56.4
2003	56.5
2004	58.6
2005	59.3
2006	59.9
2007	60.5
2008	61
2009	61.3
2010	61.7
2011	62.2
2012	62.7
2013	63.1