Answer the following question: Given the following passage  "In 1922, Egypt, which had been declared a British protectorate at the outbreak of the First World War, was granted formal independence, though it continued to be a British client state until 1954. British troops remained stationed in Egypt until the signing of the Anglo-Egyptian Treaty in 1936, under which it was agreed that the troops would withdraw but continue to occupy and defend the Suez Canal zone. In return, Egypt was assisted to join the League of Nations. Iraq, a British mandate since 1920, also gained membership of the League in its own right after achieving independence from Britain in 1932. In Palestine, Britain was presented with the problem of mediating between the Arab and Jewish communities. The 1917 Balfour Declaration, which had been incorporated into the terms of the mandate, stated that a national home for the Jewish people would be established in Palestine, and Jewish immigration allowed up to a limit that would be determined by the mandatory power. This led to increasing conflict with the Arab population, who openly revolted in 1936. As the threat of war with Germany increased during the 1930s, Britain judged the support of the Arab population in the Middle East as more important than the establishment of a Jewish homeland, and shifted to a pro-Arab stance, limiting Jewish immigration and in turn triggering a Jewish insurgency.",  answer the following question. Note that the answer is present within the text.  Question: HOw long was Iraq a British mandate
Answer:
1920, also gained membership of the League in its own right after achieving independence from Britain in 1932