# year value 1901 -0.8321583 1902 -0.3467583 1903 -0.5941164 1904 -1.0688 1905 -0.5900013 1906 -1.103976 1907 -0.6593519 1908 -0.7727331 1909 -1.135137 1910 -0.8970774 1911 -1.099403 1912 -0.3655964 1913 -1.203965 1914 0.03680209 1915 -0.8007531 1916 -0.5189116 1917 -1.187089 1918 -0.8633585 1919 -1.191259 1920 -0.602334 1921 -0.6065631 1922 -0.981761 1923 -0.6575494 1924 -0.5860702 1925 -0.8576523 1926 0.2504802 1927 -0.6782981 1928 -0.5512463 1929 -1.182247 1930 -1.131406 1931 -0.9064788 1932 -0.5076187 1933 -1.295392 1934 -0.236703 1935 -0.06163073 1936 -0.9937283 1937 -0.6285436 1938 -0.3827068 1939 -0.4430119 1940 0.1238699 1941 0.09861374 1942 -0.4515131 1943 -0.3078901 1944 -0.01150672 1945 -1.049194 1946 -0.2383641 1947 -0.9263353 1948 -0.2491603 1949 -0.5877989 1950 -0.9964364 1951 -1.158896 1952 -0.3244738 1953 -0.343574 1954 -0.5043817 1955 -0.7055764 1956 -0.7720215 1957 -1.146358 1958 0.08808896 1959 -0.150099 1960 -0.1814937 1961 -0.1353159 1962 -0.2693774 1963 0.3075616 1964 -0.6739397 1965 -0.8639475 1966 -0.594528 1967 -0.7157695 1968 -0.7854882 1969 -1.43667 1970 -0.02223084 1971 -0.7422316 1972 -1.0194 1973 -0.2489492 1974 -0.8117351 1975 -0.6997625 1976 -0.4214053 1977 -0.6114932 1978 -0.228778 1979 -0.3522209 1980 0.05231041 1981 0.3904757 1982 -0.1331268 1983 -0.05722156 1984 -0.4275528 1985 -0.7003874 1986 0.1923463 1987 0.3071405 1988 0.2090303 1989 0.09537003 1990 0.1155309 1991 0.1848991 1992 0.1326157 1993 0.07752793 1994 0.1271298 1995 0.5662416 1996 0.1621538 1997 0.261396 1998 0.521016 1999 0.7783247 2000 0.2354682 2001 0.1541919 2002 0.6848514 2003 0.6247423 2004 0.7062091 2005 0.01453993 2006 0.4759621 2007 0.8927366 2008 -0.06366 2009 0.4589666 2010 0.4098749 2011 0.08689255 2012 -0.1305888 2013 0.1376194 2014 0.5379648 2015 1.2014 2016 1.262189 2017 1.065338 2018 0.807422