Year	Number
1960	3.1723859424018284
1961	3.011997749004909
1962	2.8842887188024875
1963	2.4302360227952047
1964	2.6350853681846935
1965	3.55387727157082
1966	3.2957388721284913
1967	4.928018379829202
1968	3.4944254406250765
1969	3.3578200693891023
1970	2.0959397730623577
1971	2.6069987388327642
1972	5.2765392239555124
1973	6.230386784311479
1974	5.068920088173421
1975	17.458694900058553
1976	12.89045941865958
1977	16.90855297102919
1978	17.123609554748153
1979	8.79536805104509
1980	7.339522601569073
1981	15.610235650857987
1982	18.442079990492353
1983	9.54088453010167
1984	27.098848817474614
1985	13.723560004269126
1986	34.27795050024232
1987	29.151692671794137
1988	12.488089843897546
1989	24.459163481907257
1990	70.52769587731133
1991	47.75272097072893
1992	74.88745194683919
1993	136.2824320773199
1994	90.58538547694836
1995	84.52343074135331
1996	82.39119350922692
1997	123.95993799527223
1998	127.42205205554174
1999	104.52466598221872
2000	6.430145880271158
2001	4.092782904706631
2002	2.782833325194623
2003	3.3303299345421973
2004	3.0462279633972655
2005	2.81083735526194
2006	1.7053751382161633
2007	1.2655923448847295
2008	1.4576324451564544
2009	1.267093238752763
2010	1.3830165687121465
2011	1.8211667521000379
2012	1.5895314293356875
2013	1.7830483961471295
2014	2.2134276950592198
2015	1.8019708216608918
2016	2.9991185846995263
2017	2.246816332202783
2018	2.471931742746362