Year	Number
1960	4.568306727827313
1961	4.8858501215014805
1962	5.066919359296477
1963	4.527874340930157
1964	5.197640331966474
1965	4.872110342173742
1966	5.189377234258895
1967	4.875775321619715
1968	5.504694180475673
1969	5.812580909004224
1970	4.899374839253433
1971	3.896177313946609
1972	3.490305845098326
1973	2.5823073935059586
1974	1.2273553096716792
1975	1.4981687697364587
1976	1.7008585810228363
1977	1.6601706909869913
1978	2.308968392784699
1979	1.9633797770900405
1980	1.9486802568479535
1981	2.855617069085942
1982	2.2343998760135166
1983	2.727658957320493
1984	3.249761137366567
1985	2.685860368909191
1986	2.7082395454806054
1987	3.5014277594701575
1988	6.768099127544684
1989	4.847440220814118
1991	4.914615482968123
1992	3.445602258416162
1993	4.0686129593539695
1994	5.074959722130781
1995	5.439682520089719
1996	5.499133036824068
1997	5.994174766502809
1998	5.300738794757346
1999	4.535940071660494
2000	3.420945464211428
2001	2.832874936207801
2002	3.149397874333754
2003	4.041344515021006
2004	4.239039287780108
2005	4.408801434686448
2006	3.86925909243556
2007	3.552840979367217
2008	4.226098177645103
2009	3.7566240607870647
2010	3.6061912932655216
2011	3.3872366183361517
2012	3.187160707952936
2013	3.527696041449637
2014	3.358761235443574
2015	3.6758612585979193
2016	3.4541438697321802
2017	3.285027398071334
2018	3.144863838325434
2019	2.842852030787837
2020	2.1548953597288665
2021	2.4262517783163795
2022	2.401552140102693
2023	2.4119384808332995