Year	Number
1977	1.3919191919278227
1978	1.445161290332424
1979	1.672401433703702
1980	0.6907216494890307
1981	0.5861222074319201
1982	0.644640605296343
1983	0.9609677419354838
1984	0.994524959742351
1985	0.911406321575813
1986	1.0245087947008011
1987	0.8916792087723082
1988	1.0615438563680568
1989	0.8735561083843209
1990	0.8496962645788241
1991	0.9647480829413807
1992	1.4440398052085524
1993	1.0686241725163343
1994	1.2141586803001962
1995	1.5143857617315883
1996	1.1471558105830058
1997	1.20674099649176
1998	1.35996726837267
1999	1.482407986162404
2000	1.129505318089488
2001	1.4551142851288368
2002	1.5989156770375614
2003	1.8500999374504066
2004	1.7725293387651964
2005	1.6683294765621313
2006	1.603120869159019
2007	1.445744957525502
2008	1.328190383933975
2009	1.494890753396769
2010	1.7310948869252567
2011	1.9246997453536037
2012	1.964009768541068
2013	2.4578828470060365
2014	3.5611414987222694
2015	4.4476931512699975
2016	3.8082906342590506
2017	3.538062279823796
2018	3.1968606666743002
2019	2.60209970907881
2020	3.451347564907926
2021	4.6851224826931395
2022	3.5501304564216514
2023	3.093918020367851