Year	Number
1975	3.7916948392929535
1976	6.417051200746614
1977	9.132059640841657
1978	9.34055539932908
1979	10.345378442857825
1980	7.6631141054772165
1981	5.008631042106518
1982	5.061755595406999
1983	4.964926289124133
1984	4.660448510551963
1985	4.9951798893950565
1986	5.2319159670947
1987	5.302478885463588
1988	3.9363286399724275
1989	3.272032955293994
1990	2.0148815178393247
1991	2.924455422769256
1992	3.450664918395922
1993	4.897903604219484
1994	6.305582183067259
1995	4.6548531328228835
1996	4.599660999528725
1997	4.901232364963675
1998	5.226852430290087
1999	5.777615860799821
2000	5.677757553722197
2001	6.8965013680810445
2002	9.662074121108942
2003	11.43984591461577
2004	10.514913310641035
2005	7.9706252047415935
2006	8.3816610288186
2007	10.523592105981605
2008	7.384959375030239
2009	9.320061733771272
2010	7.478108929685144
2011	6.018912751132734
2012	5.754811331338288
2013	5.924825692665748
2014	6.472035386421023
2015	7.79338573162511
2016	8.188607488381587
2017	7.887944127944584
2018	6.712432259662597
2019	7.9663502504707155
2020	12.366784310773273
2021	9.32444553947456
2022	6.761489159852591
2023	7.757193857735355