no known episode was made for 1902, 1904, 1905, 1908, 1910, 1915, 1921, 1931, 1935, 1950, 1952, 1957, 1971, 1973, 1984 and 1996. the year 1999 is also omitted. the years 1922, 1936, 1937, 1938, 1941, 1943, 1945, 1954, 1967, 1968, 1972, 1974, 1986 and 1991, however, had two episodes, and for 1953, three.