Year	Years
1990	73.8
1991	73.9
1992	73.9
1993	73.7
1994	73.5
1995	73.2
1996	72.7
1997	72.3
1998	72.2
1999	72.2
2000	72
2001	72.6
2002	73.2
2003	73.5
2004	73.9
2005	73.9
2006	74
2007	74.4
2008	74.6
2009	74.9
2010	75.2
2011	75.4
2012	75.5
2013	75.6