Year	Number
1976	4.580884768858741
1977	4.721028720998764
1978	5.510146561412264
1979	4.011940919471523
1980	5.150240427266536
1981	4.934603631417313
1982	10.456428870507164
1983	9.885226025720558
1984	4.375252787916854
1985	5.266532474503489
1986	3.2564685839247134
1987	4.467688757006814
1988	5.214108700818142
1989	5.624148083085281
1990	5.485074731205346
1991	6.499207469004546
1992	4.761765638418739
1993	5.526147363774377
1994	5.948403834697236
1995	6.594896641807585
1996	6.960376254463633
1997	7.549326400554855
1998	6.87176625542937
1999	7.061774710614614
2000	5.709171280666174
2001	5.384982527502036
2002	6.502335472893302
2003	6.909716604055951
2004	4.940427870868556
2005	5.541965824012402
2006	5.1286163637538325
2007	5.010150846812264
2008	5.418915370614464
2009	5.060422527292212
2010	4.048511991264328
2011	5.200896031047377
2012	4.403972594318829
2013	3.8633170243024737
2014	3.605008051188226
2015	3.5597695440528896
2016	3.131591862035089
2017	3.3533634407291215
2018	3.6448581318963327
2019	3.3689606331343436
2020	2.9664034806678337
2021	2.200980222966573
2022	2.1478941778154645
2023	2.5497332039948937