Năm 1980 có bao nhiêu ngày Thứ 2

7/1/1980 14/1/1980 21/1/1980 28/1/1980 4/2/1980 11/2/1980 18/2/1980 25/2/1980 3/3/1980 10/3/1980 17/3/1980 24/3/1980 31/3/1980 7/4/1980 14/4/1980 21/4/1980 28/4/1980 5/5/1980 12/5/1980 19/5/1980 26/5/1980 2/6/1980 9/6/1980 16/6/1980 23/6/1980 30/6/1980 7/7/1980 14/7/1980 21/7/1980 28/7/1980 4/8/1980 11/8/1980 18/8/1980 25/8/1980 1/9/1980 8/9/1980 15/9/1980 22/9/1980 29/9/1980 6/10/1980 13/10/1980 20/10/1980 27/10/1980 3/11/1980 10/11/1980 17/11/1980 24/11/1980 1/12/1980 8/12/1980 15/12/1980 22/12/1980 29/12/1980