year PDO 12-yr low-pass filtered PDO 1854 -0.29682 -999.0 1855 0.15857 -999.0 1856 0.17888 -999.0 1857 0.45873 -999.0 1858 0.96178 -999.0 1859 -1.53308 -999.0 1860 -0.57778 -0.24148 1861 -0.63789 -0.20023 1862 0.16027 -0.09267 1863 0.43556 0.02900 1864 0.48385 0.12558 1865 0.07474 0.19446 1866 -0.35751 0.25428 1867 0.34817 0.31050 1868 0.47699 0.33800 1869 1.38479 0.30069 1870 0.07345 0.18596 1871 -0.08109 0.02314 1872 -0.46112 -0.13135 1873 -0.85057 -0.22572 1874 0.09651 -0.23856 1875 -0.18800 -0.18564 1876 -0.69910 -0.10720 1877 0.34441 -0.05094 1878 0.74773 -0.05041 1879 -0.01940 -0.10505 1880 -0.89101 -0.17559 1881 0.17800 -0.20526 1882 -1.02463 -0.15777 1883 -0.65114 -0.04068 1884 0.92861 0.10004 1885 1.25097 0.21333 1886 -0.20912 0.27116 1887 -0.66998 0.26688 1888 1.17960 0.19436 1889 0.74327 0.03567 1890 -0.70740 -0.21595 1891 0.60337 -0.52576 1892 -1.85861 -0.80990 1893 -1.28031 -0.96702 1894 -2.64598 -0.93597 1895 -0.48596 -0.72918 1896 0.17332 -0.42262 1897 0.18688 -0.10680 1898 0.18120 0.15810 1899 0.07844 0.35804 1900 1.27221 0.51274 1901 -0.12445 0.64821 1902 1.36374 0.77726 1903 0.33024 0.88820 1904 1.31325 0.94811 1905 1.63722 0.91533 1906 0.98249 0.76280 1907 0.61653 0.50426 1908 0.65941 0.20003 1909 -0.93268 -0.06210 1910 -0.97600 -0.21051 1911 -0.66819 -0.23197 1912 0.22802 -0.17768 1913 0.28920 -0.13032 1914 0.14270 -0.15000 1915 0.64699 -0.24227 1916 -1.56288 -0.36955 1917 -1.14266 -0.48574 1918 0.36896 -0.56809 1919 -0.52460 -0.61741 1920 -0.95044 -0.63425 1921 -1.11822 -0.60409 1922 -0.63459 -0.50315 1923 0.04416 -0.32098 1924 -0.91651 -0.07904 1925 -0.16044 0.17482 1926 2.17349 0.38743 1927 0.29127 0.52182 1928 0.25109 0.56571 1929 0.61341 0.52444 1930 0.64224 0.42213 1931 1.28897 0.30804 1932 -0.38250 0.24672 1933 -1.81540 0.28747 1934 1.01373 0.42533 1935 0.79032 0.60332 1936 2.36312 0.76081 1937 0.47698 0.87953 1938 0.21247 0.98251 1939 -0.22933 1.07963 1940 2.35331 1.12780 1941 3.00731 1.05625 1942 1.02792 0.83504 1943 -0.26118 0.51404 1944 -0.68528 0.18540 1945 -0.15940 -0.08991 1946 -0.33118 -0.31911 1947 0.69566 -0.54616 1948 -0.85492 -0.78933 1949 -1.73484 -1.01370 1950 -2.08679 -1.16361 1951 -0.97376 -1.21385 1952 -1.43602 -1.18440 1953 -0.64095 -1.10634 1954 -0.31145 -0.98258 1955 -2.17973 -0.78897 1956 -1.72768 -0.51724 1957 0.60584 -0.21591 1958 1.29396 0.02125 1959 0.67336 0.11405 1960 0.19420 0.05148 1961 -0.37986 -0.10523 1962 -1.01826 -0.26725 1963 0.02753 -0.37086 1964 -0.96439 -0.40065 1965 -0.07252 -0.37782 1966 -0.31066 -0.33983 1967 -0.56631 -0.32417 1968 0.07831 -0.35899 1969 -0.06245 -0.45299 1970 -0.27716 -0.58781 1971 -1.57386 -0.72285 1972 -0.96431 -0.81078 1973 -1.00274 -0.81552 1974 -0.32118 -0.72173 1975 -1.59847 -0.53521 1976 -0.31097 -0.28022 1977 0.40974 0.00472 1978 0.47312 0.27831 1979 0.55215 0.50812 1980 0.74222 0.67945 1981 1.26108 0.79635 1982 0.18210 0.87327 1983 1.68526 0.92373 1984 0.87524 0.94730 1985 0.29201 0.92674 1986 1.54493 0.83929 1987 1.66328 0.68194 1988 0.09015 0.49290 1989 -0.28370 0.34256 1990 -0.28763 0.29393 1991 -0.51775 0.36318 1992 1.35862 0.51366 1993 1.56729 0.67873 1994 -0.01435 0.79165 1995 0.88545 0.79902 1996 1.16343 0.66630 1997 1.97047 0.39740 1998 0.09913 0.05344 1999 -1.97211 -0.25508 2000 -1.00668 -0.42124 2001 -0.98126 -0.40709 2002 -0.12385 -0.26686 2003 0.83896 -0.11460 2004 0.15571 -0.05549 2005 0.16571 -0.13384 2006 -0.00147 -0.32799 2007 -0.63622 -0.57863 2008 -1.65682 -0.82156 2009 -0.81799 -0.99890 2010 -0.83827 -1.05662 2011 -1.84522 -0.94875 2012 -1.65271 -0.66250 2013 -0.91723 -999.0 2014 1.20548 -999.0 2015 1.79952 -999.0 2016 1.31051 -999.0 2017 0.28174 -999.0 2018 0.19393 -999.0