the mean year 365.2425 days long. While this does not synchronize the years entirely, it would require a few thousand years to accumulate a day. So that the northward equinox would have the same date in the new Gregorian calendar as it had when the Council of Nicaea made recommendations in AD 325 (), ten days were dropped so that became in 1582. This reform took a few centuries to spread through the nations that used the Julian calendar, although the Russian church year still uses the Julian calendar. Those nations that adopted this calendar on or after 1700 had to drop more than ten days: Great Britain, for instance, dropped eleven. In 1923, Milutin Milanković proposed to a synod of some Eastern Orthodox Churches at Constantinople that only centennial years that leave a remainder of 200 or 600 upon division by 900 would be leap years, decreasing the average year length to 365.24 days: these remainders were chosen to delay as much as possible the first year (after 1923) that this calendar would disagree with the Gregorian calendar, which occurs in until 2800. It was adopted by some Eastern Orthodox Churches under the names Revised Julian calendar or New calendar, but was rejected by others. Proposals The Gregorian calendar is currently used by most of the world. There is also an international standard describing the calendar, ISO 8601, with some differences from traditional conceptions in many cultures. Since the papal reform in 1582, several proposals have been offered to make the Gregorian calendar more useful or regular. Very few reforms have gained official acceptance. The rather different decimal French Republican Calendar was one such official reform, but was abolished twelve years later by Napoleon. After World War II, the newly formed United Nations continued efforts of its predecessor, the League of Nations, to establish the proposed World Calendar but postponed the issue after a veto from the government of the United States, which was mainly based upon concerns of religious groups about the proposed days that would be outside the seven-day week cycle ("blank days") and thus disrupt having a sabbath every seven days. Independently the World Council of Churches still tries to find a common rule for the date of Easter, which might be eased by a new common calendar. Reformers cite several problems with the Gregorian calendar: It is not perennial. Each year starts on a different