Year	Number
1960	1.7226947228263405
1961	2.288909765208254
1962	2.2929589271816515
1963	2.8047107109012477
1964	3.427017669572023
1965	3.570677532962801
1966	2.3572016750563995
1967	2.5898555246659374
1968	1.5292137157980827
1969	2.138846291622755
1970	2.516139591794712
1971	3.4630774610770696
1972	1.8633566778081112
1973	1.1564560035321887
1974	1.0113018014726614
1975	1.319440585312056
1976	1.510147147479518
1977	1.3969720890921102
1978	1.6021607081401992
1979	1.3301891952387601
1980	1.6724374468651209
1981	2.826011394342785
1982	4.1234608806044495
1983	2.233156519186913
1984	3.0093710555576636
1985	2.398993225740174
1986	2.131050649505183
1987	1.8737565113943329
1988	2.4008369901145343
1989	2.9196967375239296
1990	3.5921554147603114
1991	4.818388229398924
1992	4.636453633286976
1993	4.047288199037696
1994	3.9442307366522273
1995	3.835607764153671
1996	3.92613673836992
1997	3.903511889010199
1998	3.5623586885180565
1999	3.6921569089999666
2000	3.555670479003051
2001	3.3143028865016246
2002	10.498225552624358
2003	3.3716979149402704
2004	2.6684712186639303
2005	2.554179811571359
2006	2.8877975916462875
2007	2.305847242080754
2008	2.1522485711788173
2009	1.5389913915129134
2010	2.2206055918259042
2011	2.0222088618161638
2012	1.6010824608648748
2013	1.5813471385585263
2014	1.5420221849523248
2015	1.8236919700471859
2016	1.9931001394498598
2017	1.8034289805912904
2018	1.9312061202098
2019	2.0928096642755363
2020	1.9487546159162017
2021	2.103766915223582
2022	2.452976812209926
2023	2.452802749028119