Year	Number
1981	7.160628665099058
1982	14.83380603991239
1983	13.425434803833333
1984	13.887942387628557
1985	11.254525167528309
1986	6.941209395327622
1987	3.3814993052754256
1988	3.6965722344878893
1989	5.682999851789925
1990	5.538766132946504
1991	5.474120634643638
1992	4.826754101035569
1993	4.411470374370711
1994	4.958583111418392
1995	5.263871158952472
1996	6.392285605003915
1997	7.232130233220659
1998	6.179971943670638
1999	5.988465161269861
2000	6.296817438321616
2001	6.502294326228157
2002	6.885986490901625
2003	6.482450419088029
2004	5.520119881498259
2005	5.797365912604422
2006	3.9337354805265794
2007	4.310498967004732
2008	5.127510865018035
2009	3.7915549863494014
2010	3.6153047782089844
2011	3.684380318025387
2012	3.3724096646205477
2013	3.1739105242389094
2014	3.2691924191185318
2015	2.2177476978994393
2016	2.4816630223803933
2017	1.846486958995756
2018	1.9198526213902687
2019	1.6203928172199522
2020	1.3357188033324854
2021	1.4151027610089786
2022	1.5001627526723775
2023	1.526698014281475