Year	Number
1967	1.742764773556898
1968	1.7203188485066006
1969	1.9561803201633048
1970	1.897209678494065
1971	1.8239534248420426
1972	1.6879880217470962
1973	1.5251105185384513
1974	1.255059946274855
1975	1.267444686800065
1976	1.496952892797149
1977	1.9562858036627981
1978	1.8596935577580098
1979	1.5242573012495515
1980	1.465884462467602
1981	1.6974467469028065
1982	2.15187345706348
1983	6.0009680026536945
1984	13.889274630289986
1985	18.583735918879885
1986	22.78738441941603
1987	29.745184245077212
1988	43.69252733083874
1989	23.231905083382436
1990	8.940374327500473
1991	22.907495064343813
1992	10.445415817094775
1993	6.9577364791486636
1994	3.466160793548874
1995	1.0579351508062358
1996	1.8758457146294323
1997	1.975998930522368
1998	3.1455258688887886
1999	2.627662497127629
2000	2.545663477702766
2001	1.3677611554411
2002	4.677954435196637
2003	5.014265613389199
2004	5.220499695152581
2005	5.664139467039482
2006	4.285521512517432
2007	3.246902249450143
2008	2.626640517664731
2009	2.767444876136059
2010	2.912733963294395
2011	2.5133374812398594
2012	2.441326263183991
2013	3.512706829006489
2014	4.614429930685389
2015	9.428416038766139
2016	6.822414898512929
2017	5.535966346662805
2018	4.429048307378025
2019	3.9630015683705166
2020	4.227173973392166
2021	2.420533732512743
2022	2.354018710488953
2023	1.6789187996692354