Year	Number
1973	1.4583426708275642
1974	1.4791539058629104
1975	1.8159208801582907
1976	1.670516030737737
1977	1.1836364857049761
1978	1.4239823954731217
1979	1.8117404956959338
1980	1.7451748557546924
1981	1.524921988201899
1982	2.170478172985438
1983	2.1196516174476967
1984	1.9907259119571137
1985	2.5457603544008554
1986	2.6461616823916914
1987	2.178750665990179
1988	1.8246267541120857
1989	2.404491460155954
1990	2.398142690134134
1991	3.0241383812433913
1992	3.084691478144469
1993	3.262588423320881
1994	3.7811159928775204
1995	5.254780018427241
1996	4.448327050565286
1997	4.281870550711999
1998	4.818249024910442
1999	4.81892737544917
2000	4.488922177307982
2001	4.372277239136629
2002	5.458694043901874
2003	5.18832696152125
2004	4.288022790767317
2005	4.16705753228428
2006	4.074743618086755
2007	3.9678584713376965
2008	3.3417117610861773
2009	5.553059318086558
2010	5.312451573274188
2011	4.612271708190542
2012	5.0846228241824925
2013	5.06578285780785
2014	4.436303982252518
2015	4.960017786246961
2016	5.630061197000367
2017	6.800105132341685
2018	5.850373967420688
2019	6.15533668726693
2020	7.74348081215887
2021	6.35573448487691
2022	5.087836600625799
2023	5.4368541774403205