1
2
3
4
5
6
7
8
9
10
11
12
1950
-3.0
-2.8
1951
-2.7
-2.9
1952
1953
1954
-2.6
1955
-1.9
-2.0
1956
1957
-1.7
1958
-1.6
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
-1.5
0.2
0.5
1973
1974
1975
1.1
1976
1977
1.2
1978
1.3
1.4
1979
1.5
2.0
1980
1981
1.8
1.9
1982
2.1
1983
1984
2.4
2.6
1985
2.8
1986
3.0
1987
3.1
3.4
1988
3.6
1989
3.3
1990
1991
2.2
2.3
1992
2.7
1993
2.9
1994
1995
3.5
3.8
1996
3.9
3.2
3.7
1997
1998
1999
4.0
4.1
2000
4.2
4.4
4.5
2001
4.6
4.7
2002
4.8
4.9
2003
5.2
5.4
2004
5.5
5.6
2005
5.7
5.8
2006
5.9
6.0
2007
6.1
2008
2009
2010
6.2
2011
6.3
2012
6.4
2013
2014