Year	Years
1990	64.5
1991	64.9
1992	65
1993	64.9
1994	64.7
1995	64.1
1996	62.9
1997	61.6
1998	60.1
1999	58.6
2000	57.1
2001	55.7
2002	54.6
2003	53.7
2004	53.3
2005	53.1
2006	53.3
2007	54.1
2008	55
2009	55.8
2010	56.7
2011	57.5
2012	58.8
2013	60.4