Year	Number
1963	3.6158658200452147
1964	2.730301226223971
1968	5.177341034017765
1974	3.825032607496357
1975	2.6524730434890236
1976	2.2228946619387333
1977	2.7671658436023514
1978	2.3364923550522296
1979	3.7638908062263514
1980	3.389496367599032
1981	1.966098852331653
1982	2.0472506754084554
1983	2.2636300803262346
1984	1.9792735502967598
1985	3.3790711060465037
1986	4.477441403891496
1987	6.074098257552605
1988	6.159198425570598
1989	7.983148867931844
1990	7.4599354452000295
1991	8.570655048510213
1992	8.770566888848881
1993	10.647246298861148
1994	10.454105237967898
1995	9.100203586965481
1996	10.609582390882847
1997	8.663376255820292
1998	9.85580270275549
1999	9.529827837362236
2000	9.44814416650204
2001	9.868439898354534
2002	8.143474665547892
2003	6.598257633553944
2004	5.260593819497442
2005	5.068397764413055
2006	5.9217672073621745
2007	5.828114584033722
2008	4.791559236004031
2009	5.8880962643702395
2010	5.108226351543201
2011	4.869156359268181
2012	4.992234737452516
2013	4.853904257109924
2014	4.671278051841818
2015	5.1344972102238176
2016	6.065967998800452
2017	5.382622727674274
2018	4.841460489126821
2019	5.331462226349768
2020	6.645746050761952
2021	5.57583036925199
2022	4.557208958986715
2023	5.204162252785262