Year	Number
1975	10.926389689573766
1976	7.884048391117525
1977	6.822080447092474
1978	7.685806745042685
1979	9.005101290354741
1980	7.334433114787755
1981	5.864660523686358
1982	5.421477592266902
1983	6.270664867646316
1984	5.821033558825063
1985	6.670050839161747
1986	5.638402645153255
1987	5.967655360631912
1988	4.17266909174079
1989	4.363573423016616
1990	5.887408411608853
1991	6.050258349792978
1992	6.273084912867072
1993	6.643921029756551
1994	7.258058357255035
1995	6.3994063446145235
1996	7.277479829092757
1997	6.136086132040839
1998	5.253780606250484
1999	5.557394370514379
2000	4.909010405683117
2001	4.576994407263635
2002	5.089345323263502
2003	6.266744167537784
2004	5.582262465745239
2005	5.400402858924229
2006	5.650156593947039
2007	7.507616011649482
2008	6.435980618890267
2009	9.316112832297907
2010	7.942302897013118
2011	7.7817157256781115
2012	8.482478342859402
2013	8.252997064121468
2014	8.365326312210865
2015	10.050210996302571
2016	11.028632024857947
2017	10.129292630405136
2018	9.07872808895395
2019	8.715263673441735
2020	10.956412509400563
2021	8.126463972927562
2022	6.19985257002586
2023	6.915946017829597