Year	Years
1984	42.1
1985	41.1
1986	40
1987	39
1988	38
1989	37.1
1990	36.1
1991	35.1
1992	34.1
1993	33.2
1994	32.2
1995	31.3
1996	30.3
1997	29.4
1998	28.5
1999	27.6
2000	26.7
2001	25.9
2002	25.1
2003	24.3
2004	23.5
2005	22.8
2006	22
2007	21.3
2008	20.7
2009	20
2010	19.3
2011	18.7
2012	18.1
2013	17.5