Year	Years
1990	77
1991	77
1992	77
1993	77
1994	77
1995	77
1996	77
1997	77.1
1998	77.1
1999	77.1
2000	77.2
2001	77.3
2002	77.5
2003	77.9
2004	78.3
2005	78.8
2006	79.3
2007	79.9
2008	80.4
2009	80.9
2010	81.3
2011	81.6
2012	81.7
2013	81.8