Year	Number
1964	0.49498173708332677
1965	0.7201534655214162
1966	0.9646587046161567
1967	1.2373561887112963
1968	0.9870540921957468
1969	0.6524823344379934
1970	0.7122769392251097
1971	0.7493456628100628
1972	1.267821047039009
1973	1.5620925184226102
1974	1.5954927732014155
1975	1.553846325925105
1976	1.8320994573760958
1977	1.294064331886681
1978	2.9343361832307204
1979	3.7119401830708205
1980	7.695778572693633
1981	9.657457001471636
1982	10.543112674110139
1983	3.472057833715921
1984	2.2130317446717993
1985	1.664479348858323
1986	1.1894439686028295
1987	1.0218217190358232
1988	0.8498201173557758
1989	0.8120991027076832
1990	0.7586850790732371
1991	0.7302128791893885
1992	0.8410497270213154
1993	0.9313974010211169
1994	1.0722183726419052
1995	1.2550949945082528
1996	1.2030578645320738
1997	1.331488428107311
1998	1.2740852933222955
1999	1.2179398490740576
2000	1.434036977609436
2001	1.584942705290798
2002	1.5624002558713384
2003	1.4542863288445496
2004	1.7002348566006005
2005	2.3115308159363295
2006	2.609708910114942
2007	2.587636088644612
2008	3.0284439440702378
2009	1.8115798287512264
2010	1.7319921197101042
2011	2.3358391508532153
2012	2.377550707517343
2013	2.5359900619454674
2014	3.4677458070041642
2015	3.19156719450083
2016	4.081085396234255
2017	3.4830531878879327
2018	2.8470383590870485
2019	2.6784616461516415
2020	1.752499027229299
2021	1.7583931219026776
2022	1.7086229444752556
2023	1.331329560199271