Year	Number
1970	1.3077593723
1971	1.4068584714
1972	1.5059575705
1973	1.6050566696
1974	1.7041557687
1975	1.8032548678
1976	1.9023539669
1977	2.001453066
1978	2.1005521651
1979	2.1996512642
1980	2.2987503633
1981	2.3978494624
1982	2.4969485615
1983	2.5960476606
1984	2.6951467597
1985	2.7942458588
1986	2.8933449579
1987	2.992444057
1988	3.0915431561
1989	3.1906422552
1990	3.2897413543
1991	3.3888404534
1992	3.4879395525
1993	3.5870386516
1994	3.6861377507
1995	3.7852368498
1996	3.8843359489
1997	3.983435048
1998	4.0825341471
1999	4.1816332461
2000	4.2807323452
2001	4.3989755885
2002	4.5172188317
2003	4.635462075
2004	4.7537053182
2005	4.8719485615
2006	4.9901918047
2007	5.108435048
2008	5.2266782912
2009	5.3449215344
2010	5.4631647777
2011	5.5944856146
2012	5.7345248474
2013	5.8309721011
2014	5.9326503923
2015	6.2705972101
2016	6.3147340889
2017	6.3147340889
2018	6.3147340889
2019	6.3147340889
2020	6.3147340889