Year	Years
1990	77.6
1991	77.8
1992	78.1
1993	78.4
1994	78.6
1995	78.9
1996	79.1
1997	79.3
1998	79.5
1999	79.6
2000	79.7
2001	79.8
2002	80
2003	80.1
2004	80.3
2005	80.5
2006	80.7
2007	80.9
2008	81.1
2009	81.2
2010	81.5
2011	81.6
2012	81.7
2013	81.8