Detailed Instructions: 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.
Problem:Passage: With no official figures available, it is estimated that 600,000-900,000 persons fled the country during the Lebanese Civil War . Although some have since returned, this permanently disturbed Lebanese population growth and greatly complicated demographic statistics. Another result of the war was a large number of internally displaced persons. This especially affected the southern Shia community, as Israeli invasion of southern Lebanon in 1978, 1982 and 1996 prompted waves of mass emigration, in addition to the continual strain of occupation and fighting between Israel and Hezbollah . Many Shias from Southern Lebanon resettled in the suburbs south of Beirut. After the war, the pace of Christian emigration accelerated, as many Christians felt discriminated against in a Lebanon under increasingly oppressive Syrian occupation. According to a UNDP study, as much as 10% of the Lebanese had a disability in 1990. Other studies have pointed to the fact that this portion of society is highly marginalized due to the lack of educational and governmental support of their advancement.
Question: How many years are between the first time Israel invaded Southern Lebanon and the last time they invaded southern Lebanon?
Answer type: Number
Solution:
18.