Year	Number
1975	0.8311836904585432
1976	1.5669391741585206
1977	4.408938717861373
1978	4.3800397308587495
1979	4.139031412758634
1980	1.4942195112926355
1981	1.9373471175271646
1982	1.9644300018771101
1983	1.6639368065391442
1984	2.797462393103146
1985	2.2591161635110395
1986	1.8325479437770518
1987	1.4229840657127666
1988	1.0596257155935742
1989	1.137559189599382
1990	1.6636303605819192
1991	2.2852170354491688
1992	2.8778804604808665
1993	4.2803679824949565
1994	4.389913239351036
1995	3.995922163408471
1996	3.6767597516988273
1997	3.5143002012996396
1998	3.391094911639534
1999	2.756792708118093
2000	1.5871443482330112
2001	2.1716479107869913
2002	2.7624482885758814
2003	3.489627582061665
2004	2.7945283297053343
2005	3.1433521612546826
2006	2.7582639695247577
2007	3.110093988282739
2008	1.8590891866479937
2009	5.215486742334387
2010	5.343544317769718
2011	3.460796015547953
2012	3.6889781526359484
2013	3.847603894056019
2014	3.9246838037597787
2015	3.4845771458090202
2016	2.797731517217334
2017	3.4241305335599637
2018	2.8177324793296052
2019	3.364920738027057
2020	3.2874468562880086
2021	1.5949945032514063