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 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 2010 2020 2024 2030 2040 2050 2060 2070 2080 2090 2100 2200 2300 2400 2500 2600 3000 January February March April May June July August September October November December -- starts at 1980-12-29