Y \ X
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
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1860
1859
1858
1857
1856
1855
1854
1853
1852
1851
1850
1849
1848
1847
1846
1845
1844
1843
1842
1841
1840