Year	Years
1990	75.1
1991	75.3
1992	75.6
1993	75.9
1994	76.2
1995	76.6
1996	76.9
1997	77.2
1998	77.5
1999	77.9
2000	78.2
2001	78.5
2002	78.8
2003	79.1
2004	79.4
2005	79.8
2006	80.1
2007	80.4
2008	80.7
2009	80.9
2010	81
2011	81.1
2012	81.1
2013	81.1