Year	Number
1960	3.224082443564034
1961	3.786181139122316
1962	4.185427257322682
1963	4.890980392156862
1964	7.207498383968972
1965	6.65160584781858
1966	11.064100058628103
1967	9.417134306023195
1968	8.861344537815127
1969	12.12689075630252
1970	12.299894220673764
1971	11.594716660039639
1972	11.273121052682393
1973	7.426100771687142
1974	8.930865233764568
1975	11.847166411456586
1976	8.13823805636925
1977	3.3999378131389877
1978	1.8242111047678538
1979	1.935884134560548
1980	4.560580884620635
1981	3.7647652255198474
1982	4.045890828133205
1983	5.126074444857433
1984	3.3299481074951913
1985	3.9537382043959517
1986	4.995908817061611
1987	6.689395844616711
1988	8.884590398605344
1989	7.810005474472732
1990	5.077726655592135
1991	3.698828306826004
1992	3.0139640397443004
1993	1.997331657642929
1994	1.8673396307609282
1995	2.396965260201162
1996	2.631481098571136
1997	2.7695710783012424
1998	2.9337314772879712
1999	3.666505085222054
2000	5.548552974671161
2001	4.5269588153934075
2002	3.8161906952254325
2003	3.1867433228047886
2004	3.8484796497666403
2005	3.7191654456256438
2006	4.092962329067681
2007	3.6072662347632845
2008	5.372014579100049
2009	2.935061192260508
2010	2.570744509598256
2011	4.209723805439476
2012	4.0688766555711435
2013	4.430159351325749
2014	4.580628193917031
2015	5.793215037180722
2016	7.634001671800447
2017	6.461148236085575
2018	7.767774398579729
2019	6.920506369174337