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.
Input: Passage: The Kuwait-Najd War erupted in the aftermath of World War I. The war occurred because Ibn Saud wanted to annex Kuwait. The sharpened conflict between Kuwait and Najd led to the death of hundreds of Kuwaitis. The war resulted in sporadic border clashes throughout 1919-1920. Following the Kuwait-Najd War, Ibn Saud imposed a trade blockade against Kuwait for 14 years from 1923 until 1937. The goal of the Saudi economic and military attacks on Kuwait was to annex as much of Kuwait's territory as possible. At the Uqair conference in 1922, the boundaries of Kuwait and Najd were set. Kuwait had no representative at the Uqair conference. Ibn Saud persuaded Sir Percy Cox to give him two-thirds of Kuwait's territory. More than half of Kuwait was lost due to Uqair. After the Uqair conference, Kuwait was still subjected to a Saudi economic blockade and intermittent Saudi raiding.
Question: How many years were there sporadic border clashes?
Answer type: Number
Output:
2.