Year	Number
1975	11.672713884325129
1976	7.403618044391345
1977	6.976282513205998
1978	6.981582986144026
1979	6.821290175473971
1980	7.473882911409353
1981	9.558036210975807
1982	9.677676650135803
1983	10.261972932233377
1984	8.198139173072038
1985	9.621958717611768
1986	6.079988790064457
1987	5.764033189033189
1988	6.661981736713742
1989	6.63913848420522
1990	6.357996387257431
1991	6.277909428376758
1992	5.673236295498803
1993	5.559779322234152
1994	6.151406305726662
1995	6.2413312338213744
1996	7.358539970962395
1997	7.058543019198565
1998	6.800208567517192
1999	6.970176500247014
2000	6.993782814325995
2001	6.476650116239992
2002	6.216811786798903
2003	6.045116764850464
2004	5.265403024350365
2005	6.7429974860666775
2006	6.850140740709398
2007	6.4117788697830225
2008	7.434115519214672
2009	6.255981409779286
2010	5.398403865545854
2011	5.383942496281109
2012	5.116225616274341
2013	6.358703706076997
2014	4.878144796312714
2015	4.172687402337962
2016	4.380371418258302
2017	4.278751947368254
2018	5.055727673391299
2019	5.077267444737912
2020	4.998385621677327
2021	3.066903920019927
2022	3.552430934442921
2023	3.616906981174833