Year	Number
1970	1.1110976234482222
1971	1.5933624271272762
1972	2.0908592932076746
1973	2.6878196062681354
1974	1.5978425173924904
1975	2.1133428254034903
1976	1.5630317358652968
1977	2.1382577318993428
1978	2.517038300582363
1979	2.1889416641798385
1980	1.975539122659172
1981	1.8560337547255887
1982	1.991859407161363
1983	2.146777206905989
1984	1.8929254300228138
1985	2.3913418545179677
1986	2.355288649234019
1987	2.3782245071283437
1988	2.0520061872350506
1989	2.034294255588524
1990	2.882067576473276
1991	3.0198430182703873
1992	3.449568006288553
1993	3.6069713258041296
1994	3.806190574123856
1995	3.0360529756818657
1996	2.3337846186278317
1997	1.3943972591034175
1998	1.712077792714152
1999	1.8272966567222184
2000	1.6694198404595397
2001	1.7627456856243993
2002	2.114477446493305
2003	1.9791495177505691
2004	1.79316727665871
2005	1.6075282934692403
2006	1.5757908161509928
2007	1.4325072442151632
2008	1.2554443080060815
2009	2.7351163169598465
2010	2.3803753816246425
2011	2.103600281045016
2012	2.320759651306535
2013	2.8465891226759226
2014	2.6511611374718305
2015	2.844843791452628
2016	2.8738836791504303
2017	2.819087477081589
2018	2.508963663204879
2019	2.394889250731345
2020	2.766067310295893
2021	2.355362680987004
2022	2.220843599084929
2023	2.0362693662094027