Year	Number
1976	8.767433462107677
1977	9.109955096765628
1978	7.663921343985431
1979	8.593647186781576
1980	7.796422833909221
1981	6.843555059687759
1982	6.522211562198734
1983	4.104195071879437
1984	3.041610622503048
1985	2.245418135013762
1986	3.161009328662676
1987	4.639402974763413
1988	4.088443949282194
1989	4.507933687098703
1990	5.027848854357344
1991	5.654791015642304
1992	6.258696527825686
1993	7.405495875847997
1994	6.072508427127202
1995	4.669443979208792
1996	4.257225905272285
1997	4.137290426284244
1998	6.569614623581991
1999	6.151447217744176
2000	6.491274744020487
2001	7.3665905522712976
2002	7.407489686325594
2003	7.713095519062734
2004	7.738907707804435
2005	6.701434234506563
2006	7.665498471165618
2007	6.457351691979968
2008	6.619582993424813
2009	6.5653625588974105
2010	6.010522143636735
2011	6.744538209879148
2012	7.608926343093206
2013	8.56836277441355
2014	8.435011413246741
2015	12.533760736371534
2016	10.288564796268158
2017	9.353802523866044
2018	6.614643338935898
2019	7.458683432408884
2020	12.479785099312236
2021	6.722982720862563
2022	7.1199491450594605
2023	10.415314490109006