Year	Years
1990	77
1991	77.4
1992	77.7
1993	78
1994	78.2
1995	78.4
1996	78.6
1997	78.9
1998	79.1
1999	79.3
2000	79.7
2001	80.1
2002	80.4
2003	80.7
2004	81
2005	81.2
2006	81.4
2007	81.5
2008	81.5
2009	81.6
2010	81.7
2011	81.8
2012	81.8
2013	81.8