It was a Monday.
December 31st, 2009 was a Thursday.
December 31st, 1951 fell on a Monday.
December 31st, 1959 fell on a Thursday.
Sunday
It was a Tuesday.
December 31 2002 was a Tuesday.
December 31st, 1979 was a Monday.
December 31st, 1969 was a Wednesday.
December 31st, 1884 fell on a Wednesday.
December 31, 1964 was a Thursday.
December 31st, 1941 fell on a Wednesday.
December 31 1949 was a Saturday.