Question: when was the last time the social security cap was raised
[{'answer': '2018', 'provenance': [{'wikipedia_id': '4994437', 'title': 'Social Security Wage Base', 'start_paragraph_id': 2, 'start_character': 3, 'end_paragraph_id': 2, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]