Year	Number
1964	4.954516498420243
1965	5.812907032954773
1966	4.286323060413393
1967	3.4320072212609904
1968	3.8674448275777062
1969	5.732274236299489
1970	7.5177794829223625
1971	5.275320941751607
1972	6.323981341545843
1973	3.366731801356559
1974	2.490771813565177
1975	4.507588452202442
1976	4.185110976708322
1977	4.835813810205138
1978	5.266767925184405
1979	3.7484020997858347
1980	3.4507364639799225
1981	4.276150619122693
1982	6.03827936001553
1983	8.640088995429961
1984	12.266623888330784
1985	9.586419960565593
1986	12.56402599306301
1987	12.244082024697628
1988	15.524356411965112
1989	13.125066102582421
1990	14.177338091251233
1991	6.4889502153076375
1992	7.515796813858499
1993	6.84511387769732
1994	4.005412029469222
1995	3.7277528836481406
1996	2.460661018346932
1997	1.7982205964374367
1998	2.4159716464510907
1999	3.3403588925521506
2000	1.5289830126832633
2001	1.5858186795571436
2002	1.4155491248123102
2003	1.202423476155367
2004	1.106824073959657
2005	0.9388538764979985
2006	0.822926454394913
2007	0.7524576336044219
2008	0.7272598349756364
2009	0.6471764700019935
2010	0.6530594170240571
2011	0.7113588321568896
2012	0.7082458391386829
2013	0.7469183712853538
2014	0.9099600150913197
2015	0.9037739087489599
2016	1.045152546392049
2017	1.2869102394111638
2018	1.6329225237578178
2019	1.9267694413566887
2020	2.3543779813996153
2021	2.644695296903573
2022	2.249936530094092
2023	2.205332566886383