Year	Years
1990	72.1
1991	71.8
1992	71.7
1993	71.6
1994	71.5
1995	71.2
1996	70.7
1997	70.2
1998	69.6
1999	69.1
2000	69
2001	69.1
2002	69.4
2003	70
2004	70.4
2005	70.6
2006	70.8
2007	70.8
2008	70.7
2009	70.3
2010	70.1
2011	70
2012	70
2013	70