Year	Years
1990	70.8
1991	70.3
1992	69.6
1993	69
1994	68.5
1995	68.2
1996	68.1
1997	68.1
1998	68
1999	68.1
2000	68.2
2001	68.1
2002	68.1
2003	68.2
2004	68.4
2005	68.8
2006	69.2
2007	69.8
2008	70.1
2009	70.2
2010	70.2
2011	70.1
2012	70.1
2013	70.2