Question: what are the biggest sources of revenue for the federal government
[{'answer': 'individual income taxes', 'provenance': [{'wikipedia_id': '3874731', 'title': 'United States federal budget', 'start_paragraph_id': 8, 'start_character': 180, 'end_paragraph_id': 8, 'end_character': 203, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}, {'answer': 'corporate taxes', 'provenance': [{'wikipedia_id': '3874731', 'title': 'United States federal budget', 'start_paragraph_id': 8, 'start_character': 301, 'end_paragraph_id': 8, 'end_character': 316, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}, {'answer': 'Social Security / Social Insurance taxes'}]