Year	Number
1974	6.4671608968111585
1975	3.3966975688616814
1976	3.1032661149812375
1977	2.2706639259542936
1978	3.7726928123892614
1979	5.011688098988566
1980	4.278059988421044
1981	2.7691165817000436
1982	3.0141081617237213
1983	2.815496621399907
1984	2.223175172751825
1985	1.9385567902706817
1986	2.4567752868532096
1987	2.469000442948623
1988	2.5449486542469666
1989	3.5371539250442643
1990	3.1611868376464045
1991	2.859720296529176
1992	2.9828871152678587
1993	2.511973499490838
1994	3.4011342767198056
1995	3.7202786416770697
1996	4.014818434206298
1997	3.9115922183397
1998	4.106471634755383
1999	5.466124157574571
2000	4.157387387100615
2001	4.599965003187009
2002	5.641866864641108
2003	5.245592967627594
2004	4.073836552226253
2005	4.7402159936857915
2006	4.8064152432318785
2007	4.789164514030521
2008	3.889573723542147
2009	5.447236993418608
2010	4.941784672245362
2011	3.991206447599051
2012	5.4870978438459685
2013	5.436584271531912
2014	5.438660397689137
2015	5.430644396024444
2016	5.395350620401849
2017	4.767734107166237
2018	4.197020479838756
2019	5.15104842585452
2020	4.579672168030529
2021	4.360695515813167
2022	3.7100414480644552
2023	4.127203294391262