Year	Number
1976	7.657307735
1977	7.671607509
1978	7.6859072829
1979	7.7002070569
1980	7.7145068308
1981	7.7288066048
1982	7.7431063788
1983	7.7574061527
1984	7.7717059267
1985	7.7860057006
1986	7.8003054746
1987	7.8146052486
1988	7.8289050225
1989	7.8432047965
1990	7.8574534633
1991	7.8718043444
1992	7.8861041184
1993	7.9004038923
1994	7.9147036663
1995	7.9290034402
1996	8.0281836089
1997	8.1273637776
1998	8.2265439463
1999	8.325724115
2000	8.4249042837
2001	8.6095668425
2002	8.7942294014
2003	8.9788919603
2004	9.1635545192
2005	9.3482170781
2006	9.532879637
2007	9.7175421959
2008	9.9022047548
2009	10.0868673137
2010	10.2715298726
2011	10.4566640772
2012	10.4566640772
2013	10.4566640772
2014	10.4566640772
2015	10.4566640772
2016	10.4566640772
2017	10.4566640772
2018	10.4566640772
2019	10.4566640772
2020	10.4566640772