Year	Number
1976	5.857406208741634
1977	4.577644785237828
1978	3.3241522392330807
1979	4.58458377138488
1980	4.267918425308666
1981	5.699937103875369
1982	6.356749311023645
1983	7.960819798374659
1984	12.732616919254179
1985	5.661649801962416
1986	3.7010801527808073
1987	3.3180224820230144
1988	2.440240999860352
1989	2.3987036074987134
1990	2.3702198361795914
1991	3.4347382781985427
1992	3.885771142080317
1993	5.48330886296924
1994	6.670134616087121
1995	7.236545605648574
1996	5.013340062117505
1997	5.496452645384386
1998	7.84370344222849
1999	5.6140190674198065
2000	3.6617185103075633
2001	4.426350997289503
2002	4.458270218337077
2003	6.3255395614015315
2004	12.561362462704297
2005	9.052639688817804
2006	6.6161365467789235
2007	7.99953732610141
2008	5.917791730522662
2009	4.897834495469227
2010	4.795364412286143
2011	4.641617924233832
2012	4.228632906996378
2013	3.0745611864372835
2014	2.744079222720376
2015	3.287308239265308
2016	3.9155388684303434
2017	4.708414722415235
2018	5.1233327017595744
2019	5.687325269466195
2020	5.075987817932334
2021	4.727049017278145
2022	4.262144473454811
2023	4.694200514289808