Year	Number
1960	2.850394710102463
1961	1.5954596758496309
1962	2.3561274979555384
1963	3.243278323655865
1964	2.182037403768875
1965	2.4917251058730367
1966	2.35935416211375
1967	2.6321598659573597
1968	4.038080932729478
1969	4.4219624983761605
1970	4.739545368230977
1971	7.138113329783562
1972	6.973019726280744
1973	5.542095537848921
1974	20.397848459759125
1975	8.166579655181698
1976	4.3763721851077
1977	4.057348269317904
1978	5.7966178099284384
1979	6.561509640231326
1980	6.654650333183636
1981	8.212363636622504
1982	9.242003982405034
1983	12.006320545382227
1984	10.759470577168193
1985	11.048742924893881
1986	11.146984428637975
1987	13.098284261354506
1988	5.361898251215572
1989	5.6921681044336765
1990	6.508175545789476
1991	8.266250002549883
1992	7.157225511622138
1993	6.868513927326658
1994	6.433790635606508
1995	6.08454608191164
1996	6.489139031229218
1997	10.454538438868676
1998	3.5409282483042297
1999	3.737648465609242
2000	3.794460960990793
2001	5.75988369774693
2002	5.737179858341267
2003	4.84755622547391
2004	4.184765533411024
2005	4.737047057492799
2006	5.033198805295769
2007	5.220568036892392
2008	6.4196805827257615
2009	4.53726335455961
2010	4.9149589747399505
2011	5.148999807446661
2012	4.9708387160488465
2013	5.074367035506761
2014	5.437687523301999
2015	5.418906819576301
2016	5.6031337117179465
2017	5.754221502265882
2018	6.089354194455093
2019	6.115626265774178
2020	6.113508506922805
2021	6.818645962662288
2022	6.873715313410847
2023	7.104449647406872