From 1929 to 1931, the Soviet Union mandated a five-day week, with each day designated by color as a state rest day for a different 20% of the workforce; families usually did not share rest days. Three weeks a year were six or seven days, because interrupted by holidays. From 1931 to 1940, the Soviets mandated a six-day week, with state rest days for all upon the 6th, 12th, 18th, 24th, and 30th of each Gregorian month, as well as upon March 1. This also necessitated varying weeks of five to seven days over the year.