Year	Years
1990	63.3
1991	62.7
1992	61.9
1993	60.8
1994	59.2
1995	57.7
1996	56.2
1997	54.8
1998	53.5
1999	52.2
2000	50.8
2001	49.8
2002	48.9
2003	48.3
2004	47.8
2005	47.7
2006	47.8
2007	48.4
2008	49
2009	49.6
2010	50.4
2011	51.9
2012	54.1
2013	56