Year	Number
1982	6.898465976414494
1983	7.689395595706827
1984	6.661202751738194
1985	4.096440095323341
1986	4.570698960591721
1987	5.511124638885031
1988	4.507456657546254
1989	4.282277885236358
1990	6.028876803131316
1991	7.076718317005492
1992	4.168198456918672
1993	4.495220336718976
1994	5.015126968675793
1995	5.052766792769959
1996	5.947028835524059
1997	11.07500232065392
1998	11.376853145807523
1999	10.300542859897778
2000	8.405593685034795
2001	9.980529301509618
2002	12.263266866834858
2003	9.855390348249076
2004	11.216461927134048
2005	12.437703676769331
2006	13.591927876678385
2007	16.067840305743058
2008	17.189329617639657
2009	23.087780647952105
2010	19.90378955100239
2011	17.505368322538793
2012	17.377527224982586
2013	18.003565194798064
2014	17.49224607420508
2015	16.543696409238333
2016	15.335414623835383
2017	14.12127565815297
2018	12.036615288394325
2019	12.580039212197978
2020	13.731598805076292
2021	10.804643897344892
2022	10.193271398845006
2023	11.196214702192083