Question: when was the drinking age set to 21
[{'answer': 'By mid-1988', 'provenance': [{'wikipedia_id': '19197423', 'title': 'U.S. history of alcohol minimum purchase age by state', 'start_paragraph_id': 4, 'start_character': 361, 'end_paragraph_id': 4, 'end_character': 372, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19197423', 'title': 'U.S. history of alcohol minimum purchase age by state', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 1108, 'bleu_score': 0.9765707625998521, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3596675500979050622}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19197423', 'title': 'U.S. history of alcohol minimum purchase age by state', 'section': 'Section::::Abstract.', 'start_paragraph_id': 4, 'end_paragraph_id': 4, 'meta': {'evidence_span': ['By mid-1988, all 50 states and the District of Columbia had raised their purchase ages to 21 (but not Puerto Rico, Guam, or the Virgin Islands, see Additional Notes below). South Dakota and Wyoming were the final two states to comply with the age 21 mandate', 'In 1984, Congress passed the National Minimum Drinking Age Act, which required states to raise their ages for purchase and public possession to 21 by October 1986 or lose 10% of their federal highway funds. By mid-1988, all 50 states and the District of Columbia had raised their purchase ages to 21 (but not Puerto Rico, Guam, or the Virgin Islands, see Additional Notes below). South Dakota and Wyoming were the final two states to comply with the age 21 mandate. The current drinking age of 21 remains a point of contention among many Americans, because of it being higher than the age of majority (18 in most states) and higher than the drinking ages of most other countries. The National Minimum Drinking Age Act is also seen as a congressional sidestep of the tenth amendment. Although debates have not been highly publicized, a few states have proposed legislation to lower their drinking age, while Guam raised its drinking age to 21 in July 2010.', 'From 1976 to 1983, several states voluntarily raised their purchase ages to 19 (or, less commonly, 20 or 21), in part to combat drunk driving fatalities. In 1984, Congress passed the National Minimum Drinking Age Act, which required states to raise their ages for purchase and public possession to 21 by October 1986 or lose 10% of their federal highway funds. By mid-1988, all 50 states and the District of Columbia had raised their purchase ages to 21 (but not Puerto Rico, Guam, or the Virgin Islands, see Additional Notes below). South Dakota and Wyoming were the final two states to comply with the age 21 mandate. The current drinking age of 21 remains a point of contention among many Americans, because of it being higher than the age of majority (18 in most states) and higher than the drinking ages of most other countries. The National Minimum Drinking Age Act is also seen as a congressional sidestep of the tenth amendment. Although debates have not been highly publicized, a few states have proposed legislation to lower their drinking age, while Guam raised its drinking age to 21 in July 2010']}}]}, {'provenance': [{'wikipedia_id': '3424880', 'title': 'List of alcohol laws of the United States', 'section': 'Section::::Abstract.', 'start_paragraph_id': 2, 'end_paragraph_id': 2, 'meta': {'evidence_span': ["As of July 1988, all 50 states and the District of Columbia had a minimum purchase age of 21, with some grandfather clauses, and with the exception of Louisiana's complicated legal situation that was not resolved until July 2, 1996.", 'After Congress passed the Act, states not in compliance had a portion of their federal highway budget withheld. South Dakota and Wyoming were the final two states to comply, in mid-1988. However, most states continue to allow those under 21 to drink in certain circumstances. Examples are some states like Tennessee and Washington, which allow those under 21 to drink for religious purposes. States including Oregon and New York allow those under 21 to drink on private non-alcohol selling premises. Unlike on the mainland, the U.S. territories of Puerto Rico and the U.S. Virgin Islands have a minimum purchase and drinking age of 18', "The bill would force all states to raise their drinking age from 18, 19, or 20 to 21. States that did not choose to raise their drinking age to 21 would risk losing 10% (Changed to 8% in 2012) of federal highway funding as a penalty. As of July 1988, all 50 states and the District of Columbia had a minimum purchase age of 21, with some grandfather clauses, and with the exception of Louisiana's complicated legal situation that was not resolved until July 2, 1996. Prior to 1988, the minimum purchase age varied by jurisdiction. After Congress passed the Act, states not in compliance had a portion of their federal highway budget withheld. South Dakota and Wyoming were the final two states to comply, in mid-1988. However, most states continue to allow those under 21 to drink in certain circumstances. Examples are some states like Tennessee and Washington, which allow those under 21 to drink for religious purposes. States including Oregon and New York allow those under 21 to drink on private non-alcohol selling premises. Unlike on the mainland, the U.S. territories of Puerto Rico and the U.S. Virgin Islands have a minimum purchase and drinking age of 18"]}}]}]