You did not indicate a full year...
12/31/50: Sunday
12/31/51: Monday
12/31/52: Wednesday
12/31/53: Thursday
12/31/54: Friday
12/31/55: Saturday
12/31/56: Monday
12/31/57: Tuesday
12/31/58: Wednesday
12/31/59: Thursday
As you can tell, through the 2 day skips in 1952 and 1956 they were leap years.
Hope this helps !
31 December 1980 was a Wednesday.
31 December 1931 was a Thursday.
31 December 1993 was a Friday.
31 December 1965 was a Friday.
December 31 1999 was a Friday.
December 31 1945 was a Monday.
December 31, 1968 was a Tuesday.
December 31, 1869 was a Friday.
31 December 2001 was a Monday.
December 31 1982 was on a Friday.
December 31 1976 was on a Friday.
December 31, 2005 was a Saturday.