Year	Number
1960	6.7317577287384305
1961	8.186127503144046
1962	8.968206360132474
1963	8.153160951173902
1964	8.887762185921147
1965	10.59417170379261
1966	11.008699940765712
1967	11.852384924464216
1968	11.354198486126208
1969	13.967452290634439
1970	14.310472629309807
1971	12.453304885565036
1972	11.025043237770763
1973	10.639253621179478
1974	11.34696360748833
1975	14.521838749141626
1976	24.52171908149614
1977	12.668522374155122
1978	14.485065214502969
1979	14.435881713167353
1980	14.660677847114135
1981	17.318389120263962
1982	32.49520268328888
1983	9.253658876885394
1984	6.6935996385544625
1985	8.76643780452142
1986	5.3567602467236926
1987	2.7990369692916905
1988	3.194939162950245
1989	5.425373622380273
1990	5.756877834816967
1991	4.529986796521344
1992	5.140764252344381
1993	4.523739579118466
1994	19.69899725932359
1995	5.160648350253939
1996	4.833235568348317
1997	4.923942773696502
1998	4.538773788782482
1999	5.15609606746129
2000	4.454638149466764
2001	4.254720724473211
2002	3.8245183760895554
2003	3.2128876308175687
2004	3.192245668658443
2005	3.1494325992208743
2006	3.262092098561739
2007	3.136565939871429
2008	3.069073659724842
2009	2.6894887098325957
2010	2.6867280589552203
2011	2.4288525588146044
2012	2.2525478937346457
2013	2.331785061291455
2014	2.3147884114040083
2015	2.3999366752432088
2016	2.2843812671792163
2017	2.5413170313449167
2018	2.598905619538409
2019	2.6193452006293563
2020	2.4497947719856152
2021	2.7238061752199823
2022	3.0421803947614463
2023	3.5921007004506205