Year	Number
1975	6.551425041023716
1976	6.172464491523995
1977	4.985282383439412
1978	4.850168720631666
1979	4.223033602195182
1980	3.3436385092701295
1981	2.722106156095022
1982	3.026598288299128
1983	2.477844295822688
1984	2.5394388178791476
1985	3.0223266355851477
1986	3.7410401410561733
1987	3.819996750123738
1988	3.6140213550125306
1989	4.256666200925804
1990	4.411704474333264
1991	4.8411657551853535
1992	5.097361457510222
1993	5.383096062417566
1994	5.352055766975115
1995	5.027914016913838
1996	5.105213763495213
1997	4.051764323385816
1998	6.39744899631093
1999	6.685707466570566
2000	5.072972331183547
2001	5.2498144282551
2002	5.77678521095063
2003	5.428499874585673
2004	5.128473861668657
2005	4.352284521635826
2006	5.08069119941126
2007	5.930955964436477
2008	6.0802354647904036
2009	9.813958287708491
2010	9.072560138628303
2011	7.741520068760139
2012	7.269062261773224
2013	6.510198413091403
2014	6.663611793487318
2015	7.354632050015997
2016	8.341364387464967
2017	8.781629591675237
2018	7.788249166491374
2019	8.858427252902908
2020	12.132893118810754
2021	8.988309109015377
2022	7.136897738796201
2023	7.5866255652945025