Year	Number
1964	1.1286174612715134
1965	0.8819135724065078
1966	0.8391126550783964
1967	0.9647446262581857
1968	1.1747194368030072
1969	1.342239209352351
1970	1.1464383324517635
1971	0.8658070321032642
1972	1.1867803155864407
1973	1.3910529390491742
1974	0.8805037764653016
1975	0.9280803192099509
1976	1.522405451753708
1977	1.0985494017605502
1978	1.6491394779702615
1979	22.56307423810386
1980	9.294962624929665
1981	13.955942499227472
1982	6.61529106980371
1983	20.909118635414362
1984	20.967913160127914
1985	38.056906311115995
1986	2.9347658389725333
1987	1.8852681074554527
1988	3.0846756067389354
1989	3.0496864074070746
1990	1.1826295018052162
1991	1.0986387978271126
1992	0.8826326133491048
1993	0.8637519216553436
1994	0.8529046004078384
1995	0.9030981261974944
1996	0.9671876195614609
1997	1.2148453817569482
1998	1.1586170122246326
1999	1.1598507444626875
2000	1.416607717405346
2001	1.4234788635209068
2002	1.5044037741654437
2003	2.70170878610496
2004	2.225072737768963
2005	2.1529436313831694
2006	2.262791616780165
2007	2.3029914670638063
2008	3.7374130335321434
2009	1.857857339443846
2010	2.3152977158923096
2011	2.2108952458192435
2012	2.058327828662827
2013	2.361247860551646
2014	2.9306184025105693
2017	3.389652286737138
2018	3.4386909773154173
2019	3.135171132067189
2020	2.4786479704439635
2021	1.7596759215962026
2022	2.0629795285084307
2023	2.008391381848842