Year	Number
1975	29.7444117909
1976	34.4089213445
1977	39.0734308982
1978	43.7379404518
1979	48.4024500054
1980	53.0669595591
1981	57.7314691127
1982	62.3959786664
1983	67.06048822
1984	71.7249977736
1985	76.3895073273
1986	81.0540168809
1987	85.7185264345
1988	90.3830359882
1989	95.0475455418
1990	99.7120550954
1991	104.3765646491
1992	109.0410742027
1993	113.7055837563
1994	119.7702377772
1995	120.1531748152
1996	124.356576721
1997	128.4798290142
1998	132.8435301452
1999	130.893222905
2000	134.2238845846
2001	138.5163416155
2002	145.6852791878
2003	128.6401282394
2004	125.654109894
2005	125.9631311782
2006	125.9631311782
2007	125.9631311782
2008	125.9631311782
2009	125.5623831151
2010	125.1616350521
2011	124.760886989
2012	124.360138926
2013	124.360138926
2014	124.360138926
2015	124.360138926
2016	124.360138926
2017	124.360138926
2018	124.360138926
2019	124.360138926
2020	124.360138926