Year	Years
1990	53.3
1991	53.2
1992	53
1993	52.7
1994	47.3
1995	52.4
1996	51.3
1997	51.9
1998	52.1
1999	52.2
2000	52.5
2001	52.8
2002	52.9
2003	53.3
2004	53.8
2005	54.2
2006	54.6
2007	55.1
2008	55.4
2009	55.8
2010	56.3
2011	56.7
2012	57.1
2013	57.5