Year	Years
1990	72.4
1991	72.3
1992	72.1
1993	72.1
1994	72.2
1995	72.2
1996	72.6
1997	72.9
1998	73.2
1999	73.6
2000	73.9
2001	74.1
2002	74.2
2003	74.3
2004	74.3
2005	74.3
2006	74.4
2007	74.6
2008	74.8
2009	75.1
2010	75.2
2011	75.2
2012	75.2
2013	75.2