闰年
Leap years have two dominical letters because the dominical letter changes end February. The first letter covers January and February, the second covers March to December. For leap years, the outer circle will show two dominical letters. The cycle of the dominical letters for common years is twice every 11 years and once every 6 years, while for leap years is once every 28 years. 2008 (leap year starting on Tuesday) is the year 1 of the cycle, while 2007 (common year starting on Monday) is the year 28 of the cycle. From 1980 to 2007, respectively, there were: