Year	Years
1990	73.1
1991	72.7
1992	68.1
1993	68.2
1994	70.6
1995	67.1
1996	73
1997	73.7
1998	74.3
1999	74.8
2000	75.2
2001	75.6
2002	75.7
2003	75.8
2004	75.8
2005	75.7
2006	75.6
2007	75.6
2008	75.9
2009	76.2
2010	76.5
2011	77
2012	77.3
2013	77.5