Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

After an initial loss to Labor at the 1946 election, Menzies led the Liberals to victory at the 1949 election, and the party stayed in office for a record 23 years—still the longest unbroken run in government at the federal level. Australia experienced prolonged economic growth during the post-war boom period of the Menzies Government (1949–1966) and Menzies fulfilled his promises at the 1949 election to end rationing of butter, tea and petrol and provided a five-shilling endowment for first-born children, as well as for others. While himself an unashamed anglophile, Menzies' government concluded a number of major defence and trade treaties that set Australia on its post-war trajectory out of Britain's orbit; opened Australia to multi-ethnic immigration; and instigated important legal reforms regarding Aboriginal Australians.
How many years did the Liberals stay in office after the 1949 election?