Sym454 -9000 -8000 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1980 1990 2000 2010 2020 2024 2030 2040 2050 2060 2070 2080 2100 2200 2300 2400 2500 2600 3000 January February March April May June July August September October November December -- starts at 1960-01-04