Definify.com

Webster 1913 Edition

adv.

In a proportionate manner; with due proportion; proportionally.

adv.

With due proportion; according to a settled or suitable rate or degree.

proportionately ‎(comparative more proportionately, superlative most proportionately)

proportionately in The Century Dictionary, The Century Co., New York, 1911
proportionately in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913