Question: when did they start vaccinating for whooping cough
[{'answer': 'the 1940s', 'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 4, 'start_character': 402, 'end_paragraph_id': 4, 'end_character': 411, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'the 1920s', 'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 53, 'start_character': 236, 'end_paragraph_id': 53, 'end_character': 245, 'bleu_score': 1.0, 'section': 'Section::::History.:Discovery.\n'}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 45, 'start_character': 0, 'end_paragraph_id': 45, 'end_character': 453, 'bleu_score': 0.972782728923768, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12620784926811093905}, 'section': 'Section::::Epidemiology.\n'}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 55, 'start_character': 0, 'end_paragraph_id': 55, 'end_character': 1066, 'bleu_score': 0.9874601949752461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12620784926811093905}, 'section': 'Section::::History.:Vaccine.\n'}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 411, 'bleu_score': 0.772508866576571, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12620784926811093905}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'start_paragraph_id': 53, 'start_character': 0, 'end_paragraph_id': 53, 'end_character': 526, 'bleu_score': 0.9776501033621461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12620784926811093905}, 'section': 'Section::::History.:Discovery.\n'}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'section': 'Section::::Epidemiology.\n', 'start_paragraph_id': 45, 'end_paragraph_id': 45, 'meta': {'evidence_span': ['After vaccinations were introduced in the 1940s', 'the disease worldwide. This is despite generally high coverage with the DTP and DTaP vaccines. Pertussis is one of the leading causes of vaccine-preventable deaths worldwide. About 90% of all cases occur in developing countries. Before vaccines, an average of 178,171 cases was reported in the U.S., with peaks reported every two to five years; more than 93% of reported cases occurred in children under 10 years of age. The actual incidence was likely much higher. After vaccinations were introduced in the 1940s, pertussis incidence fell dramatically to approximately 1,000 by 1976. Incidence rates have increased since 1980. In 2015, rates in the United States were 20,762 people.\rhighlight sentence(s) containing evidence, not only the answer']}}]}, {'provenance': [{'wikipedia_id': '170927', 'title': 'Whooping cough', 'section': 'Section::::Abstract.', 'start_paragraph_id': 4, 'end_paragraph_id': 4, 'meta': {'evidence_span': ['The pertussis vaccine became available in the 1940s.', 'The pertussis vaccine became available in the 1940s.', 'An estimated 16.3\xa0million people worldwide were infected in 2015. Most cases occur in the developing world, and people of all ages may be affected. In 2015, pertussis resulted in 58,700 deaths down from 138,000 deaths in 1990. Outbreaks of the disease were first described in the 16th century. The bacterium that causes the infection was discovered in 1906. The pertussis vaccine became available in the 1940s.\rhighlight sentence(s) containing evidence, not only the answer']}}]}]