Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
proportion (n.)
Some commentators have long and wrongly argued that proportion cannot be used to indicate size or magnitude or to mean “part” or “portion” but should be used only to express a ratio of one thing to another. Actually, it has long been Standard in all three senses: The run on the bank quickly reached epidemic proportions [“size”]. A noticeable proportion [“part”] of the residents failed to attend the meeting. The proportion [“ratio”] of those voting on the resolution was about three in favor, one opposed.
