Year	Number
1977	10.368241548965033
1978	8.12770611413247
1979	6.629890530411216
1980	6.900276057875767
1981	7.76543893861082
1982	5.04195533043686
1983	5.24103746832488
1984	6.038963275961693
1985	9.822431234446992
1986	11.208660581486486
1987	7.946239070310758
1988	8.318378175355763
1989	10.004506718345182
1990	8.142691277201038
1991	6.727343913014989
1992	15.366749207460387
1993	16.26531951928332
1994	9.42169966336409
1995	9.059134105850903
1996	8.191683210566335
1997	7.567195456054183
1998	8.342164077124135
1999	9.0585030613134
2000	9.561590994405249
2001	8.587338898931328
2002	7.180928553576855
2003	6.125372198635542
2004	4.70180636698265
2005	4.154104896793993
2006	4.0105608336832335
2007	3.429459119275684
2008	3.478190578903424
2009	3.6416587509870353
2010	3.6795562402252497
2011	4.049419471356205
2012	4.555693109725808
2013	4.6025004651673935
2014	5.126851380184074
2015	6.56543645307633
2016	7.53105784624782
2017	7.662718455714417
2018	8.55372626690545
2019	8.76793699791273
2020	9.270142591403465
2021	10.596724819437007
2022	11.741270484336527
2023	11.758724445063757