Year	Years
1990	70.1
1991	69.8
1992	69.4
1993	69.2
1994	69.2
1995	69.4
1996	69.7
1997	70.1
1998	70.6
1999	71
2000	71.4
2001	71.7
2002	71.9
2003	72.1
2004	72.1
2005	72.2
2006	72.2
2007	72.3
2008	72.5
2009	72.6
2010	72.9
2011	73.2
2012	73.5
2013	73.8