Year	Number
1960	2.055490507283566
1961	1.7425485802473222
1962	2.3916594206947224
1963	2.2475052189066997
1964	2.2963167710039776
1965	2.499343741497896
1966	3.146436441105935
1967	3.5748869278357303
1968	2.859289129734365
1969	3.4501345978709548
1970	3.3651137822837485
1971	3.234093421209425
1972	4.442976636885402
1973	5.847166532433045
1974	5.168995003384363
1975	8.612907070432007
1976	35.29967899527008
1977	25.7670468746151
1978	16.3701494391158
1979	12.588109549276325
1980	10.88715743620258
1981	15.858880278691847
1982	16.940066668183047
1983	34.44985963293964
1984	12.518107906328297
1985	7.083831750360653
1986	17.384795570692553
1987	11.520608559608382
1988	18.894131422925984
1989	27.21654409893278
1990	16.918637986809696
1991	23.432093133598073
1992	6.2468075792196345
1993	5.802019401017858
1994	3.187987147178296
1995	4.1497613373424365
1996	3.7226925160345727
1997	5.8608734651744525
1998	5.921480670237681
1999	7.74182678432228
2000	3.4428088124597234
2001	2.2515571763889537
2002	2.8263039749076704
2003	3.6219604871041495
2004	2.571565094996664
2005	2.3068506398119974
2006	2.361781527517062
2007	3.17441501507636
2008	3.3639810500133382
2009	2.6135687569233768
2010	2.308670961633641
2011	2.692943269838779
2012	3.2380857819532625
2013	3.545525694750326
2014	2.5185454189762253
2015	2.29882154509286
2016	2.1584705494144454
2017	2.0434775368611993
2018	2.387072238745343
2019	2.461698106079989
2020	2.517530032696001
2021	2.1961736220129056
2022	2.5066546694315828
2023	2.5911355411342685