In 1919, following the Treaty of Versailles, the city was restituted to France in accordance with U.S. President Woodrow Wilson's "Fourteen Points" without a referendum. The date of the assignment was retroactively established on Armistice Day. It is doubtful whether a referendum in Strasbourg would have ended in France's favour since the political parties striving for an autonomous Alsace or a connection to France accounted only for a small proportion of votes in the last Reichstag as well as in the local elections. The Alsatian autonomists who were pro French had won many votes in the more rural parts of the region and other towns since the annexation of the region by Germany in 1871. The movement started with the first election for the Reichstag; those elected were called "les députés protestataires", and until the fall of Bismarck in 1890, they were the only deputies elected by the Alsatians to the German parliament demanding the return of those territories to France. At the last Reichstag election in Strasbourg and its periphery, the clear winners were the Social Democrats; the city was the administrative capital of the region, was inhabited by many Germans appointed by the central government in Berlin and its flourishing economy attracted many Germans. This could explain the difference between the rural vote and the one in Strasbourg. After the war, many Germans left Strasbourg and went back to Germany; some of them were denounced by the locals or expelled by the newly appointed authorities. The Saverne Affair was vivid in the memory among the Alsatians.

Answer this question, if possible (if impossible, reply "unanswerable"): In what year were the last Reichstag elections held in Strasbourg?
unanswerable