Year	Years
1990	74.2
1991	74.2
1992	74.1
1993	73.9
1994	73.9
1995	73.9
1996	73.9
1997	74
1998	74.1
1999	74.1
2000	74.1
2001	74.1
2002	74
2003	73.8
2004	73.6
2005	73.5
2006	73.5
2007	73.6
2008	73.6
2009	73.5
2010	73.4
2011	73.5
2012	73.6
2013	73.7