Year	Number
1960	0.59099516348856
1961	0.7663376104155715
1962	0.944629036832935
1963	2.390802325885185
1964	2.8594176891863494
1965	3.541654633319856
1966	4.16767140905072
1967	4.909222719536027
1968	5.899539747945734
1969	9.094353921940128
1970	17.171324641267223
1971	14.419313640670703
1972	13.414423966728098
1973	9.620490071111153
1974	6.422205012725034
1975	26.062520333236364
1976	50.1850769530489
1977	73.09102335525785
1978	70.21972446039483
1979	33.796241788255735
1980	51.889864071324716
1981	189.22103632709747
1982	129.84525517524082
1983	144.45702882629814
1984	166.3215563506261
1985	217.30205487249543
1986	53.409687084938284
1987	303.4354939130199
1988	259.83590993429704
1989	303.2504062148214
1990	628.8876973959026
1991	1021.8483341555567
1992	48.403103561590775
1993	44.37944345986694
1994	17.675484259188693
1995	7.280444579372389
1996	8.566597213190327
1997	12.282699917135199
1998	11.274295749331644
1999	5.31421839449178
2000	9.783252247900592
2001	33.547841950113295
2002	8.589682214477953
2003	5.222061399950473
2004	2.7218030990133446
2005	2.959185365844473
2006	4.939838850365773
2007	7.099811950878719
2008	7.847079921153953
2009	9.984659938696948
2010	11.935560346352862
2011	57.71291299907051
2012	50.83072730656979
2013	47.16124810744512
2014	48.123107784671376
2015	54.68715203996747
2016	47.73245052633625
2017	54.4256657578295