Year	Number
1960	4.391844965704076
1961	3.835753336654097
1962	3.5107325570441836
1963	3.068000511024163
1964	3.5221077240071015
1965	4.043369819432267
1966	3.6732609195525496
1967	3.752235838897652
1968	5.189053026884632
1969	5.6317564978469274
1970	4.294445605355643
1971	6.240910847762138
1972	3.2481005118423054
1973	2.4411319392553152
1974	2.3547577284946155
1975	3.25337766362915
1976	2.6084976358723657
1977	2.425876509578185
1978	2.4276122042346215
1979	2.3802545551542953
1980	2.3015797788733297
1981	4.052065707826629
1982	6.141777684067515
1983	3.0612974784845157
1984	3.983359104224477
1985	2.9708593792533198
1986	2.519179763901043
1987	2.7828959552096313
1988	2.6920474370421363
1989	1.9973815434333797
1990	2.1023756761719334
1991	2.080158960024398
1992	2.3118913139853308
1993	2.2356377541943013
1994	2.3936995587092134
1995	2.8633969621389976
1996	2.86144163749475
1997	2.8369418345962756
1998	3.0192881917559777
1999	1.3681179894470517
2000	3.220094958596672
2001	4.657089383471113
2002	6.775651056863549
2003	6.88477337943267
2004	6.929779803769453
2005	5.554165248137581
2006	6.650686340224243
2007	4.444682384453975
2008	4.334715257994025
2009	5.475293556149017
2010	9.218704458549507
2011	9.531361307879267
2012	13.264161090248887
2013	8.646760193561173
2014	10.958600214020818
2015	16.52693615145373
2016	11.490277411979713
2017	17.857480847519803
2018	18.78787364999589
2019	15.021390069385737
2020	6.802280060381219
2021	6.908834772293339
2022	7.1160090366650195
2023	14.259805420824229