Year	Years
1990	75.4
1991	75.6
1992	75.8
1993	75.7
1994	75.8
1995	75.9
1996	76.3
1997	76.8
1998	77
1999	77.1
2000	77.1
2001	77.1
2002	77.2
2003	77.3
2004	77.6
2005	77.7
2006	77.8
2007	78.1
2008	78.2
2009	78.3
2010	78.5
2011	78.7
2012	78.8
2013	78.9