 This has happened in whole-day steps, as leap days which were dropped in certain centennial years in the Gregorian calendar continued to be present in the Julian calendar.Thus, in the year 1700 the difference increased to 11 days; in 1800, 12; and in 1900, 13.Since 2000 was a leap year according to both the Julian and Gregorian calendars, the difference of 13 days did not change in that year