Year	Number
1983	5.516994936355969
1984	4.258157738954284
1985	3.4116328922018515
1986	3.6735407728979865
1987	5.209191757768842
1988	5.680052331451825
1989	6.489336859416056
1990	12.211995781338358
1991	3.932040462801098
1992	4.745809752411652
1993	3.1723530994157008
1994	3.1524196158805187
1995	1.7972449394467405
1996	2.2284228526759744
1997	2.5214302396789714
1998	2.2919842592183404
1999	2.040005386643482
2000	1.8903094825054014
2001	2.2594257249103182
2002	2.959548650359721
2003	3.063689395085466
2004	3.029475085798411
2005	3.0294310604082746
2006	2.8179867812029404
2007	3.217319819887339
2008	2.649546531587345
2009	1.7909768407785898
2010	1.7844989760450287
2011	1.813723928534682
2012	1.688747407323102
2013	1.7597127788876048
2014	1.9198286257642594
2015	2.143194803250121
2016	2.9250796998368545
2017	2.9827116270597056
2018	3.023983555705054
2019	2.9959979328886077
2020	2.6355454318944305
2021	3.017399266365899
2022	2.8088635682315766
2023	2.769952773641601