Year	Number
1980	0.97799511
1981	1.0920945395
1982	1.206193969
1983	1.3202933985
1984	1.434392828
1985	1.5484922575
1986	1.6206776109
1987	1.6928629643
1988	1.7650483176
1989	1.837233671
1990	1.9094190243
1991	1.9816043777
1992	2.0537897311
1993	2.1259750844
1994	2.1981604378
1995	2.2703457911
1996	2.3425311445
1997	2.4147164978
1998	2.4869018512
1999	2.5590872046
2000	2.7649318896
2001	2.9707765747
2002	3.1766212598
2003	3.3824659448
2004	3.5883106299
2005	3.7941553149
2006	4
2007	4.0596984515
2008	4.119396903
2009	4.1790953545
2010	4.238793806
2011	5.1911165444
2012	6.1434392828
2013	7.0957620212
2014	8.0480847596
2015	8.0480847596
2016	8.0480847596
2017	8.0480847596
2018	8.0480847596
2019	8.0480847596
2020	8.0480847596