Year	Number
1960	2.461549703203987
1961	2.3503365142625356
1962	2.77556187046135
1963	2.9028527034205096
1964	3.369578685821664
1965	2.9704128172143607
1966	3.8009049773755654
1967	3.9976595412700893
1968	3.058471337579618
1969	3.814014598540146
1970	4.108357843137255
1971	3.713200603887658
1972	3.0196060426253615
1973	9.382430812906428
1974	2.364575414580724
1975	1.8813308802104856
1976	7.275990443024167
1977	10.823842694291505
1978	4.709383440156945
1979	16.973251486069575
1980	26.898834645669293
1981	51.52729012349559
1982	39.39456571485367
1983	77.17200821777092
1984	80.29379217273954
1985	79.37033176377557
1986	69.53979328165374
1987	46.84312586244462
1988	129.08126237623762
1989	21.501812073143864
1990	10.47261848385418
1991	1.4633011063245842
1992	1.3975944630784434
1993	1.2367588729154118
1994	1.3434844909468135
1995	1.491806076719745
1996	1.4903905646246582
1997	1.7020495408514609
1998	1.9798621986917992
1999	1.9025638787027899
2000	1.795583734132365
2001	2.1693567687735746
2002	2.326987288785077
2003	2.578563866843063
2004	3.2959469206401404
2005	3.1909964960284825
2006	3.357207150933147
2007	3.354288758723196
2008	3.2900178551547445
2009	2.0452483491108318
2010	1.9152799530294127
2011	2.113134576048845
2012	2.2100325964052066
2013	2.5618648751460698
2014	3.0980948606550895
2015	4.032350167225966
2016	3.8920282887767312
2017	3.971884215807338
2018	4.562995258069805
2019	4.7014111893598045
2020	4.535468611968064
2021	4.441282931668882
2022	4.4193129671248235
2023	5.5315657632284