Year	Number
1969	5.796608675444474
1970	5.486966977417423
1971	8.02201207790613
1972	2.7459006598400033
1973	2.9350585875100634
1974	2.3371453637295243
1975	8.123959602769649
1976	4.197089685316234
1977	2.97427371021038
1978	3.2182461224579755
1979	1.9907789407553247
1980	1.8220220471322233
1981	2.487551639656508
1982	3.7114859742619473
1983	3.3207408221236387
1984	3.0883179535421177
1985	3.5226606073978246
1986	4.1460152975096
1987	2.947294769916182
1988	4.010134735271145
1989	4.979142309335456
1990	5.35036899455139
1991	4.965623138258106
1992	5.1483679264203674
1993	5.533517201006428
1994	6.016159237843842
1995	6.58775360342356
1996	6.177000186897125
1997	6.909068576382473
1998	2.4203372038585806
1999	2.9893271633303815
2000	3.0292630820644213
2001	2.9051138434217467
2002	2.9422866653629187
2003	3.0461028543202056
2004	3.1853130808893617
2005	3.568461649768892
2006	3.543402853480343
2007	3.1696857229069315
2008	3.78516303246413
2009	3.117136608967868
2010	2.825528549981824
2011	2.9786557273767813
2012	3.1238575998592264
2013	3.5877303515254177
2014	3.1442857675918057
2015	3.2071634852839486
2016	3.231759708589077
2017	3.1101911543008955
2018	3.3530692439223277
2019	3.35767251074983
2020	3.4844102398424
2021	3.795986245584712
2022	4.185056001221507
2023	3.9579878785199734