Year	Number
1989	2.9386758261442476
1990	3.2911342342280987
1991	3.389358284627017
1992	2.410046612253006
1993	2.464737006100613
1994	2.0675269075542575
1995	1.8865354328578026
1996	2.0464570269327695
1997	2.0159265734732057
1998	1.880906393639227
1999	2.5041341473426013
2000	2.0637989879953254
2001	2.2621119006169312
2002	2.3378609912480064
2003	2.938637941043721
2004	2.564461024410546
2005	2.5929892028439627
2006	2.8524888499468375
2007	1.119222447588732
2008	1.185574650370468
2009	1.8030092472993429
2010	1.4499922990174108
2011	1.3334883743556263
2012	1.370163383529827
2013	1.5557296481305853
2014	1.6634435996683978
2015	1.6067087502618609
2016	1.900890715484147
2017	2.1037712487277536
2018	1.5905491257529842
2019	1.8105806645353708
2020	1.645551868352776
2021	1.787147181076529
2022	1.3388630960157513
2023	1.5166400409979226