Year	Years
1990	62.3
1991	62.4
1992	62.4
1993	62.2
1994	61.7
1995	60.9
1996	59.9
1997	58.8
1998	57.6
1999	56.4
2000	55
2001	53.9
2002	53
2003	52.2
2004	51.8
2005	51.9
2006	53.2
2007	55.4
2008	57.2
2009	58.5
2010	59.5
2011	60
2012	60.4
2013	60.6