Year	Number
1966	3.1083184956611825
1967	3.5119091445800468
1968	3.277378106123816
1969	3.456215911308801
1970	4.7828824950353965
1971	6.097866193333204
1972	3.6170629049903265
1973	3.59807441178043
1974	12.450087795897693
1975	11.517042943841947
1976	7.386562216143007
1977	3.5728900753883366
1978	12.20099131007441
1979	24.695689906016803
1980	105.29306997046692
1981	132.65933006635944
1982	552.4557065484059
1983	134.63778484264776
1984	73.49928058981948
1985	140.90169011774216
1986	25.185553004940395
1987	32.51383802255928
1988	11.437414694571745
1989	14.993704208574032
1990	4.396401034425987
1991	4.812566088232712
1992	3.102700600005184
1993	5.1079880331190095
1994	3.3666657041658965
1995	4.406501429859268
1996	3.0279772552898816
1997	2.352351444517149
1998	2.489111175113
1999	2.0501923072398562
2000	1.7553602812808293
2001	1.8164588427328612
2002	1.5668319614011843
2003	1.3121498804717078
2004	1.2613305974947047
2005	1.837441619662234
2006	1.8229691418446978
2007	1.7331710144597638
2008	2.1767334508722174
2009	1.9372155287635802
2010	2.0207853896354435
2011	2.2438007541894525
2012	2.2997875817705156
2013	2.155696052844129
2014	2.5656239295660908
2015	2.72344703649592
2016	2.4153800437728465
2017	1.8832510319525637
2018	2.259014444974635