Year	Number
1975	24.367293965
1976	25.2928720243
1977	26.2116192493
1978	27.144028143
1979	28.0559445336
1980	28.9951842618
1981	29.900269818
1982	30.8463403805
1983	31.7719184398
1984	32.6974964992
1985	33.6230745586
1986	34.5486526179
1987	35.4742306773
1988	36.3998087366
1989	37.325386796
1990	38.2509648554
1991	39.111649988
1992	40.0440588818
1993	40.9628061068
1994	41.8883841661
1995	42.6454683106
1996	43.4025524551
1997	44.1596365996
1998	44.9167207441
1999	45.6738048886
2000	41.0772225827
2001	40.2790395847
2002	39.4808565866
2003	38.6826735886
2004	37.8844905905
2005	35.5613238157
2006	37.8844905905
2007	40.2076573653
2008	42.5308241402
2009	44.853990915
2010	47.1771576898
2011	49.5003244646
2012	51.8234912395
2013	54.1466580143
2014	56.4698247891
2015	58.7929915639
2016	58.7929915639
2017	58.7929915639
2018	58.7929915639
2019	58.7929915639
2020	58.7929915639