Year	Number
1977	3.780974367318133
1978	3.9955303430877764
1979	4.620460926956018
1980	4.613042476288063
1981	3.076025078581275
1982	1.786484005444599
1983	0.9042833837213243
1984	1.0449501546958615
1985	1.581851713136968
1986	3.858957181203458
1987	2.722558298730621
1988	2.1998899709403297
1989	1.9586543635270726
1990	1.4865716030256397
1991	3.261088186284972
1992	3.345785515577564
1993	3.1525951713862717
1994	3.07161422055261
1995	2.6138093266235574
1996	3.2049019032544055
1997	1.9617145216129586
1998	3.07431591479305
1999	5.172271220205658
2000	4.677998400998996
2001	5.144178317819331
2002	5.112041685680622
2003	5.0444970397350035
2004	4.445549526438492
2005	4.603491495933214
2006	5.088254602502445
2007	6.740130265317621
2008	6.399534823871352
2009	9.1851180984831
2010	10.43726973921603
2011	11.599640595948559
2012	11.47387625401422
2013	11.620931882497958
2014	9.94050359217836
2015	9.898358171673781
2016	8.846561650192857
2017	7.78302270131781
2018	6.883160244926491
2019	7.720245579263841
2020	12.28544554437428
2021	9.661809662644275
2022	7.1710271113457384
2023	7.674435064674252