Year	Number
1975	3.7916948392929535
1976	6.417051200746614
1977	9.132059640841657
1978	9.340555399329082
1979	10.345378442857825
1980	7.6631141054772165
1981	5.008631042106518
1982	5.061755595407
1983	4.964926289124133
1984	4.660448510551963
1985	4.9951798893950565
1986	5.231915967094701
1987	5.3024788854635885
1988	3.9363286399724275
1989	3.272032955293994
1990	2.0148815178393242
1991	2.9244554227692556
1992	3.450664918395923
1993	4.897903604219483
1994	6.305582183067259
1995	4.6548531328228835
1996	4.599660999528726
1997	4.901232364963674
1998	5.226852430290087
1999	5.77761586079982
2000	5.677757553722196
2001	6.8965013680810445
2002	9.662074121108942
2003	11.439845914615768
2004	10.514913310641035
2005	7.9706252047415935
2006	8.381661028818598
2007	10.523592105981605
2008	7.384959375030239
2009	9.320061733771274
2010	7.478108929685141
2011	6.018912751132733
2012	5.754811331338287
2013	5.924825692665749
2014	6.472035386421023
2015	7.793385731625111
2016	8.188607488381589
2017	7.887944127944583
2018	6.712432259662597
2019	7.9663502504707155
2020	12.366784310773273
2021	9.324445539474562
2022	6.761489159852591
2023	7.757193857735353