Year	Years
1990	73.7
1991	73.2
1992	73.5
1993	73.3
1994	72.9
1995	72.7
1996	72.7
1997	73
1998	74.2
1999	74.6
2000	74.7
2001	75
2002	75.3
2003	75.5
2004	75.6
2005	75.8
2006	76
2007	76.2
2008	76.4
2009	76.7
2010	77
2011	77.3
2012	77.5
2013	77.7