This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.

Passage: Salks vaccine was then used in a test called the Francis Field Trial, led by Thomas Francis, Jr., the largest medical experiment in history at that time. The test began with about 4,000 children at Franklin Sherman Elementary School in McLean, Virginia, and eventually involved 1.8 million children, in 44 states from Maine to California. By the conclusion of the study, roughly 440,000 received one or more injections of the vaccine, about 210,000 children received a placebo, consisting of harmless culture media, and 1.2 million children received no vaccination and served as a control group, who would then be observed to see if any contracted polio. The results of the field trial were announced 12 April 1955 (the tenth anniversary of the death of President Franklin D. Roosevelt, whose Franklin D. Roosevelts paralytic illness was generally believed to have been caused by polio). The Salk vaccine had been 60-70% effective against PV1 (poliovirus type 1), over 90% effective against PV2 and PV3, and 94% effective against the development of bulbar polio. Soon after Salks vaccine was licensed in 1955, childrens vaccination campaigns were launched. In the U.S, following a mass immunization campaign promoted by the March of Dimes, the annual number of polio cases fell from 35,000 in 1953 to 5,600 by 1957. By 1961 only 161 cases were recorded in the United States.
Question: How many states chose not to particpate in the Salks vaccine?
Answer type: Number
6.

Passage: In week 4, the Lions visited their divisional rival, the Minnesota Vikings. After a scoreless first quarter, the Lions got on the board with a 29-yard field goal by Matt Prater. The Vikings responded a few minutes later with a five-yard rushing touchdown by Dalvin Cook to make the score 7-3 in favor of Minnesota at half-time. The Lions scored 11 unanswered points in the second half. First, Prater kicked a 37-yard field goal to cut the Vikings' lead to three in the third quarter. Next, Detroit regained the lead with a three-yard rushing touchdown by Ameer Abdullah, followed by a two-point conversion pass from Matthew Stafford to T. J. Jones. Both third quarter scores followed Vikings fumbles that were recovered by the Lions. Detroit's Glover Quin forced another fumble by Adam Thielen with under two minutes left in the game, which was recovered by Tahir Whitehead to end Minnesota's attempt at a possible game-tying drive.
Question: How many times did the Vikings fumble?
Answer type: Number
3.

Passage: Henry VI, elected King of the Romans since 1169, succeeded his father Frederick and was crowned Holy Roman Emperor by Pope Celestine III in 1191. In his struggle with the Princes to enforce his succession, the tide turned in his favour when the returning crusader King Richard was captured in Austria and only released against an oath of allegiance and an enormous ransom. In 1194 Henry could assert the inheritance claims of his wife Constance by conquering the Kingdom of Sicily. By declaring a new Crusade to reconquer Jerusalem, Henry aimed at an agreement with Pope Celestine III to acknowledge his rule over Sicily. In 1195 the armistice concluded by King Richard ended. Sultan Saladin had already died in 1193 and a conflict over his succession raged in the Ayyubid lands. In view of these favourable developments, the emperor hoped to continue the momentum of the previous campaign. Henry VI decided to take advantage of his father's threat of force against the Byzantine Empire, affected by the rebellions in Serbia and Bulgaria as well as by Seljuk incursions. Emperor Isaac II Angelos had maintained close ties with the Sicilian ursurper king Tancred of Lecce, he was overthrown in April 1195 by his brother Alexios III Angelos. Henry took the occasion to exact tribute and had a threatening letter sent to the Byzantine emperor in order to finance the planned Crusade. Alexius immediately submitted to the tributary demands and exacted high taxes from his subjects to pay the Crusaders 5,000 pounds of gold. Henry also forged alliances with King Amalric of Cyprus and Prince Leo of Cilicia.
Question: How many years did the armistice with King Richard last?
Answer type: Number
2.