Answer based on context:

An important element the Revolution's legacy is the 1917 Constitution. It was pushed forward by populist generals within Carranza's government to undermine the popular support that Pancho Villa and Emiliano Zapata held. It was not written by liberal elites or the military itself, but rather young radicalized professionals, giving the document some authenticity for the peasantry. The document brought numerous reforms demanded by populist factions of the revolution, with article 27 empowering the state to expropriate resources deemed vital to the nation. These included expropriation of hacienda lands and redistribution to peasants. Article 27 also empowered the government to expropriate holdings of foreign companies, most prominently seen in the 1938 expropriation of oil. In Article 123 the constitution codified major labor reforms, including an 8-hour work day, a right to strike, equal pay laws for women, and an end to exploitative practices such as child labor and company stores. The constitution strengthened restrictions on the Roman Catholic Church in Mexico. In the early 1990s, the government introduced reforms to the constitution that rolled back the government's power to expropriate property and its restrictions on religious institutions. Just as the government of Carlos Salinas de Gortari was amending significant provisions of the constitution, Metro Constitución de 1917 station was opened.

How many full decades were there between the passage of the 1917 Constitution and the enactment of of reforms that rolled back the government's power to expropriate property?
7