its every six years...because every year xmas is a day later (ths yr sun, nxt yr mon...) but every 4 yrs there is a leap year so it skips a day...\n\nthe years r:\n2005\n1999\n1993\n1987\n1981\n1975\n1969\n1963\n1957\n1951\n1945\n1939\n1933\n1927\n1921\n1915\n1909\n1903\n\nand i think that is all you want...so...yea...
How many times has Christman fell on Sun. and what years?