Year	Years
1990	72.7
1991	72.7
1992	72.9
1993	73.2
1994	73.4
1995	73.5
1996	73.7
1997	73.7
1998	74
1999	74.3
2000	74.7
2001	75.1
2002	75.5
2003	75.9
2004	76.2
2005	76.3
2006	76.3
2007	76.3
2008	76.5
2009	76.7
2010	77.2
2011	77.5
2012	77.7
2013	77.8