Detailed Instructions: This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
Q: Passage: The 2008 Research Assessment Exercise returned 26% of the 1225 staff submitted as being world-leading (4*) and a further 47% as being internationally excellent (3*). The 2008 Research Assessment Exercise also showed five subjects Pure Mathematics, Epidemiology and Public Health, Chemical Engineering, Civil Engineering, and Mechanical, Aeronautical and Manufacturing Engineering were assessed to be the best[clarification needed] in terms of the proportion of internationally recognised research quality. Question: What percentage of Imperial's staff was classified as world leading in 2008?
A:
26%