Year	Number
1984	13.6426778243
1985	13.4892573222
1986	13.3358368201
1987	13.182416318
1988	13.0289958159
1989	12.8755753138
1990	12.7221548117
1991	12.5687343096
1992	12.4153138075
1993	12.2618933054
1994	12.1084728033
1995	11.9550523013
1996	11.8016317992
1997	11.6482112971
1998	11.494790795
1999	11.3413702929
2000	11.1879497908
2001	11.2026610879
2002	11.2173723849
2003	11.232083682
2004	11.2467949791
2005	11.2615062762
2006	11.2615062762
2007	11.2615062762
2008	11.2615062762
2009	11.2615062762
2010	11.2615062762
2011	11.2615062762
2012	11.2615062762
2013	11.2615062762
2014	11.2615062762
2015	11.2615062762
2016	11.2615062762
2017	11.2615062762
2018	11.2615062762
2019	11.2615062762
2020	11.2615062762