Query: When did the RSFSR cease to be a part of the Soviet Union?
Context: The Russian Soviet Federative Socialist Republic (Russian SFSR or RSFSR; Russian: Российская Советская Федеративная Социалистическая Республика, tr. Rossiyskaya Sovetskaya Federativnaya Sotsialisticheskaya Respublika  listen (help·info)) commonly referred to as Soviet Russia or simply as Russia, was a sovereign state in 1917–22, the largest, most populous, and most economically developed republic of the Soviet Union in 1922–91 and a sovereign part of the Soviet Union with its own legislation in 1990–91. The Republic comprised sixteen autonomous republics, five autonomous oblasts, ten autonomous okrugs, six krais, and forty oblasts.