Year	Number
1974	1.2249387534683391
1975	1.4451139582638628
1976	1.939322095858094
1977	2.6454534096590376
1978	2.419358907221651
1979	3.6766101881158293
1980	3.1900618118415953
1981	3.0728889318104473
1982	3.1951206532101666
1983	2.9586925854484765
1984	3.065624381328947
1985	3.210164327351009
1986	3.538287453479904
1987	6.471450809735766
1988	4.395371977810077
1989	5.212925125990715
1990	5.390044076544248
1991	6.787679057131855
1992	5.4833435074951495
1993	4.0894053017092205
1994	3.964976562135864
1995	4.066267708398062
1996	3.970934272969437
1997	3.7050922297207585
1998	3.0534638245531633
1999	4.989635813042261
2000	3.9456377880860094
2001	3.5046741117939963
2002	4.49376463524817
2003	4.531718050873427
2004	3.5453887311932157
2005	4.035279543206039
2006	3.716736040735012
2007	5.101308939719561
2008	4.569865502089738
2009	5.824983293890442
2010	5.476732025395862
2011	5.059990401188443
2012	4.364173907063488
2013	4.077506289702712
2014	4.521703687983907
2015	5.3128407375093385
2016	7.114267992983701
2017	4.944955116864053
2018	4.9776571821737585
2019	4.992666953776216
2020	4.473808681626867
2021	5.272521173056072
2022	3.7984950498929364