Year	Number
1965	1.4023322383412764
1966	1.9241682016086499
1967	2.0317116646061724
1968	1.891640028090929
1969	2.3247796067324042
1970	1.9382062547345567
1971	2.1361014054923806
1972	2.1663772254002462
1973	1.5531319858164099
1974	1.684085987426993
1975	2.400676255074092
1976	5.0567200016907385
1977	2.0130599914019953
1978	2.595764002497859
1979	2.7369002359599865
1980	3.1049409371937413
1981	4.978834314167381
1982	9.178879371468424
1983	12.27793729016833
1984	4.536584156581629
1985	4.5502113993494735
1986	8.86675326999713
1987	5.213931654861601
1988	2.1030150365096194
1989	2.9609323948029345
1990	2.468182235062774
1991	2.715040604449344
1992	8.723545940038528
1993	7.135478486397767
1994	6.368650620287809
1995	2.3603697871321945
1996	1.6832596320670195
1997	2.469651755988494
1998	1.2345433355283881
1999	1.153617692972069
2000	1.2614953392854265
2001	1.5399618044527443
2002	2.2086143600942556
2003	2.8848940088568935
2004	3.1906354313256386
2005	2.759530075043772
2006	3.2561519117007314
2007	2.698794900401483
2008	3.91377741510539
2009	7.550450515101114
2010	4.732592414342605
2011	9.253729621444077
2012	6.34216213876574
2013	3.342212133271458
2014	2.414387565861441
2015	2.316380868790989
2016	2.0936046698666035
2017	1.919771978750913
2018	2.1357352906143836
2019	2.0914923332141693
2020	3.4591010677999274