1700
As of March 1 (O.S. February 19), where then Julian calendar acknowledged a leap day and the Gregorian calendar didn't, the Julian calendar fell one day further behind, bringing the difference to 11 days until February 28 (O.S. February 17), 1800. In Sweden, the year started in the Julian calendar and remained so until February 28. Then, by skipping the leap day, the Swedish calendar was introduced, letting February 28 be followed by March 1, giving the entire year the same pattern as a common year starting on Monday. This calendar, being ten days behind the Gregorian and one day ahead of the Julian, lasts until 1712.