Year	Number
1960	5.422099328526352
1961	6.238175589303063
1962	7.007217433956975
1963	8.476393667455818
1964	12.513103240860953
1965	14.970658452466767
1966	19.799087576280332
1967	25.1986145316534
1968	24.41858092155865
1969	16.530514923504647
1970	9.210278459046716
1971	4.872674281834401
1972	3.440034871506209
1973	2.765065531513673
1974	3.7232424835239186
1975	7.349581822995099
1976	7.7918926216850375
1977	11.019153834711751
1978	8.565894834722103
1979	6.760590408516446
1980	3.763329706444012
1981	6.598270721106164
1982	5.8791994318032685
1983	5.674363610900621
1984	6.16832864465907
1985	7.091747148996711
1986	7.24807642717387
1987	7.021481660261349
1988	6.481894226671411
1989	4.561086980305479
1990	4.689941758584769
1991	6.184091930153895
1992	5.89370875789986
1993	5.793685711460915
1994	4.78225462173037
1995	3.9195847400041086
1996	3.7261043133139493
1997	3.5651656145708164
1998	3.774342464885324
1999	3.995563079210606
2000	3.911413330310467
2001	4.485920951082004
2002	3.2765463442498812
2003	3.002718315126975
2004	3.6390260179817746
2005	3.7306262921614133
2006	3.5571880799479447
2007	3.7164095596276776
2008	4.82182728448584
2009	4.484921824947552
2010	4.7800240921078405
2011	4.829817661269781
2012	3.669802601150878
2013	3.8144612135028737
2014	3.794355479156297
2015	4.102284292347059
2016	4.582197338226589
2017	4.297002335398383
2018	4.449246914325594
2019	4.234668629111297
2020	5.19797401714357
2021	5.3596484970393945
2022	4.068467711124866
2023	4.238184747087157