Year	Number
1973	1.458342670827564
1974	1.4791539058629104
1975	1.8159208801582907
1976	1.670516030737737
1977	1.1836364857049761
1978	1.4239823954731217
1979	2.36165950531536
1980	2.0668510288065844
1981	1.524921988201899
1982	2.170478172985438
1983	2.0467515918210664
1984	1.8777224822954863
1985	1.7990504401864318
1986	2.423032937425154
1987	2.645157041327084
1988	1.9420595137742989
1989	3.645640534546502
1990	1.6630000757387473
1991	3.7632664702366054
1992	4.196083557282545
1993	3.228201843843461
1994	4.625823286069259
1995	2.7085384577134186
1996	2.9280910836158083
1997	4.3756900831840815
1998	3.3850805056024735
1999	2.5411728615803435
2000	2.820911796730924
2001	3.449005877216233
2002	4.559115553274896
2003	4.452559806498942
2004	5.258242002084286
2005	6.724548919115324
2006	7.047703861711345
2007	6.255454554112776
2008	5.124484995955819
2009	8.683798139760516
2010	8.441539266497152
2011	6.882818037253618
2012	7.147252287513668
2013	6.8486755131164
2014	5.790718383805034
2015	5.681255464298932
2016	5.4074192409201824
2017	5.160272238071678
2018	4.21360155009546
2019	4.138428765834332
2020	5.467450286514864
2021	4.278092786590929
2022	4.039149054872194
2023	5.078213760649911