Year	Years
1990	75.4
1991	75.8
1992	76.1
1993	76.5
1994	76.7
1995	76.9
1996	77.1
1997	77.4
1998	77.8
1999	78.1
2000	78.5
2001	78.8
2002	79
2003	79.3
2004	79.5
2005	79.8
2006	80
2007	80.1
2008	80.2
2009	80.3
2010	80.5
2011	80.6
2012	80.6
2013	80.6