Year	Years
1990	51
1991	50
1992	49.1
1993	48.4
1994	47.8
1995	47.3
1996	46.8
1997	46.4
1998	46.1
1999	45.9
2000	45.7
2001	45.8
2002	46
2003	46.4
2004	47.1
2005	47.9
2006	48.8
2007	49.9
2008	52
2009	53.5
2010	54.1
2011	54.6
2012	55.6
2013	56.7