Fraction Year	Year	0-700 m (5-year average)	0-700 m (yearly average)	Month	0-2000 m (5-year average)	3-Month average	0-2000 m (yearly average)	Yearly average	Pentadal average
	1957	-6.289			-9.303
	1958	-4.893			-8.059
	1959	-5.784			-8.713
	1960	-3.387			-5.479
	1961	-2.708			-4.762
	1962	-2.604			-4.121
	1963	-3.998			-5.697
	1964	-4.666			-6.521
	1965	-5.374			-7.218
	1966	-7.159			-9.122
	1967	-7.297	-4.361		-9.059
	1968	-6.884	-5.728		-8.991
	1969	-5.413	-4.481		-7.62
	1970	-4.618	-5.298		-6.838
	1971	-3.601	-3.767		-5.627
	1972	-3.222	-5.239		-4.77
	1973	-3.129	-3.519		-4.087
	1974	-2.439	-2.775		-3.354
	1975	-1.457	-1.551		-1.398
	1976	-0.978	-2.603		-1.445
	1977	-0.183	0.032		-1.143
	1978	0.975	0.052		0.056
	1979	1.58	-0.96		0.068
	1980	1.114	1.091		-1.176
	1981	0.523	0.122		-1.383
	1982	0.486	-2.306		-1.073
	1983	0.219	-2.763		-0.974
	1984	0.49	-0.459		-0.21
	1985	0.648	0.11		0.481
	1986	1.066	-1.037		0.718
	1987	0.98	-0.893		1.023
	1988	0.76	1.088		0.844
	1989	0.803	0.903		0.412
	1990	1.566	0.177		0.517
	1991	2.712	2.646		3.036
	1992	3.702	0.572		3.899
	1993	3.876	0.684		3.84
	1994	3.218	1.51		3.409
	1995	3.779	2.264		4.543
	1996	4.174	4.544		5.033
	1997	4.251	3.245		4.996
	1998	4.513	4.304		6.233
	1999	4.559	5.943		6.234
	2000	5.629	5.857		7.286
	2001	6.182	4.117		8.284
	2002	7.173	6.789		9.481
	2003	8.012	9.952		10.173
	2004	9.127	10.24		11.806
	2005	9.105	8.412		11.996		10.171
	2006	9.314	10.43		12.423		12.638
	2007	9.451	9.478		12.664		12.394
	2008	10.227	10.052		14.102		13.257
	2009	10.443	10.126		14.587		13.431
	2010	10.642	10.367		15.229		14.537
	2011	11.494	10.869		16.681		15.394
	2012		10.941				16.187
	2013		12.601				18.65