Date mark index

What is date mark?

 

  1 2 3 4 5 6 7 8 9 10 11 12
A 1810 1834 1858 1882 1906 1930 1954 1978 2002 2026 2050 2074
B 1811 1835 1859 1883 1907 1931 1955 1979 2003 2027 2051 2075
C 1812 1836 1860 1884 1908 1932 1956 1980 2004 2028 2052 2076
D 1813 1837 1861 1885 1909 1933 1957 1981 2005 2029 2053 2077
E 1814 1838 1862 1886 1910 1934 1958 1982 2006 2030 2054 2078
F 1815 1839 1863 1887 1911 1935 1959 1983 2007 2031 2055 2079
G 1816 1840 1864 1888 1912 1936 1960 1984 2008 2032 2056 2080
H 1817 1841 1865 1889 1913 1937 1961 1985 2009 2033 2057 2081
I 1818 1842 1866 1890 1914 1938 1962 1986 2010 2034 2058 2082
K 1819 1843 1867 1891 1915 1939 1963 1987 2011 2035 2059 2083
L 1820 1844 1868 1892 1916 1940 1964 1988 2012 2036 2060 2084
M 1821 1845 1869 1893 1917 1941 1965 1989 2013 2037 2061 2085
N 1822 1846 1870 1894 1918 1942 1966 1990 2014 2038 2062 2086
O 1823 1847 1871 1895 1919 1943 1967 1991 2015 2039 2063 2087
P 1824 1848 1872 1896 1920 1944 1968 1992 2016 2040 2064 2088
Q 1825 1849 1873 1897 1921 1945 1969 1993 2017 2041 2065 2089
R 1826 1850 1874 1898 1922 1946 1970 1994 2018 2042 2066 2090
S 1827 1851 1875 1899 1923 1947 1971 1995 2019 2043 2067 2091
T 1828 1852 1876 1900 1924 1948 1972 1996 2020 2044 2068 2092
U 1829 1853 1877 1901 1925 1949 1973 1997 2021 2045 2069 2093
V 1830 1854 1878 1902 1926 1950 1974 1998 2022 2046 2070 2094
X 1831 1855 1879 1903 1927 1951 1975 1999 2023 2047 2071 2095
Y 1832 1856 1880 1904 1928 1952 1976 2000 2024 2048 2072 2096
Z 1833 1857 1881 1905 1929 1953 1977 2001 2025 2049 2073 2097