Year	Number
1976	2.355509748066271
1977	2.70223012038626
1978	1.8118537058414297
1979	1.5474506114430497
1980	1.327986261926427
1981	1.04951478523487
1982	1.1428484248693438
1983	0.9558661811894702
1984	1.0440334713111488
1985	1.1593690592737422
1986	1.105417181106504
1987	0.9684592367250958
1988	2.6508551137756275
1989	2.7383815305781565
1990	2.3218062521120784
1991	1.8393227507955265
1992	2.255083621122362
1993	2.534211363986031
1994	2.6164280379207407
1995	2.4916251931495808
1996	2.3098092706151534
1997	1.3990523086882243
1998	5.1461379565284435
1999	6.02012281185595
2000	5.812203741701083
2001	6.818679072894594
2002	7.550389516106325
2003	8.332892956877178
2004	8.543323387990998
2005	7.614907743630763
2006	7.277109972395803
2007	6.856521607182494
2008	4.464362576941872
2009	7.802920956006342
2010	6.5467233974824
2011	5.392034018807983
2012	5.769060532217691
2013	6.198459857103164
2014	6.542303729964033
2015	7.9205453756485085
2016	8.388485013513266
2017	7.558317702866552
2018	7.122151040712759
2019	7.7128923941908685
2020	9.401557712919905
2021	7.567286199376975
2022	5.941420822250485
2023	6.307756219352971