Year	Number
1968	1.5206188309415472
1969	1.4884036125817504
1970	0.9908218590398367
1971	1.547608118586089
1972	1.4906870093386488
1973	1.7524301620563112
1974	1.2242867394195331
1975	1.327835677893221
1976	1.4628577822093491
1977	1.9600148221889178
1978	1.625820949405598
1979	2.0879192773456006
1980	1.4964442458100558
1981	1.6041897441741089
1982	1.141013805002368
1983	1.279743457279579
1984	1.7233703465368935
1985	2.295996198742629
1986	2.4191608729950036
1987	1.0094888259288526
1988	1.3734505715533998
1989	0.7379291024674065
1990	0.32020870648703376
1991	2.1618425268788775
1992	1.9544475943749053
1993	1.7872015940101913
1994	0.662081492488401
1995	0.8893899881372206
1996	0.7709070692725524
1997	0.7548847827117341
1998	0.836557643327293
1999	1.0972016129818667
2000	0.8308156912160458
2001	1.5412648109909648
2002	0.6327007633607331
2003	0.4167565187047395
2004	1.1358611792872264
2005	2.070797553234675
2006	1.9898000601719743
2007	2.300612361288045
2008	1.7932416936292694
2009	3.0717524666422955
2010	2.3004401114906323
2011	2.139116075413822
2012	1.8068856567701117
2013	2.4412075483941695
2014	2.426585596510239
2015	2.681922055946659
2016	3.0045195461635688
2017	3.2605850675694
2018	3.2580276404276316
2019	3.6380176699310285
2020	5.283386888739103
2021	4.63496719728729
2022	4.1418477676032115
2023	4.515171696498255