Year	Number
1960	3.834904947526237
1961	4.075522235722965
1965	6.316019116202947
1966	5.811480187061574
1967	5.928325086385626
1968	4.60012983456931
1969	2.3358747169811322
1970	2.072863657230298
1971	2.883207467018248
1972	4.671116780811519
1973	4.312497314958777
1974	2.412654306712771
1975	2.0562612077575215
1976	2.3739283566839164
1977	2.630208084200368
1978	3.570566708297113
1979	3.824370315818847
1980	3.6159388816187428
1981	3.2614368938236176
1982	3.550505347188246
1983	3.2714693044813625
1984	2.680456712785686
1985	3.269421847962407
1986	3.904829974519342
1987	3.8966698222492906
1988	2.6001691830473326
1989	3.2908640730841063
1990	3.326927582167726
1991	3.013085579336199
1992	2.231870949290634
1993	2.5313510284654783
1994	2.3964759187224853
1995	2.4626143482821905
1996	3.2128445631720113
1997	5.669902281023234
1998	6.405877004881943
1999	5.568672999754128
2000	4.755561107232041
2001	5.405536422703896
2002	5.797619845842546
2003	6.063316852672158
2004	5.42299792893475
2005	5.163462052863435
2006	4.870392809212346
2007	4.00718095047143
2008	5.326667325444623
2009	9.73834131322506
2010	9.638565343661122
2011	8.555688562779231
2012	8.510164593786987
2013	9.135945632557897
2014	9.657984822171663
2015	10.963054251388057
2016	10.939674560960267
2017	12.01964807255802
2018	11.124718854080488
2019	12.001336142922048
2020	18.499950631808446
2021	16.896054654443276
2022	13.313698120494578
2023	15.133001606412433