In the 1980s and early 1990s, there was a significant movement in favor of the territory becoming a commonwealth, which would give it a level of self-government similar to Puerto Rico and the Northern Mariana Islands. However, the federal government rejected the version of a commonwealth that the government of Guam proposed, due to it having clauses incompatible with the Territorial Clause (Art. IV, Sec. 3, cl. 2) of the U.S. Constitution. Other movements advocate U.S. statehood for Guam, union with the state of Hawaii, union with the Northern Mariana Islands as a single territory, or independence.

Answer this question, if possible (if impossible, reply "unanswerable"): In what decade was the U.S. Constitution last modified?
unanswerable