North America Direct Revenue grew by $42.5 million, or 10.9%, in 2015 versus 2014, driven by 10.3% growth in Average PMC and a 0.5% increase in ARPPU. Average PMC growth was driven by an increase in the percentage of new users becoming paid members. growth in new users, and higher beginning PMC. ARPPU increased due to increases in mix-adjusted rates, offset by mix shifts to lower rate brands. International Direct Revenue increased by $0.4 million, or 0.2%, in 2015 versus 2014, driven by 23.8% growth in Average PMC, offset by a 19.1% decline in ARPPU. Average PMC growth was driven by an increase in the percentage of new users becoming paid members, growth in new users, and higher beginning PMC. ARPPU deceased primarily due to the effects of foreign exchange. Adjusting for foreign exchange effects, International Direct Revenue grew 18.5%, and International ARPPU declined 4.4% due to a mix shift to lower rate brands, partially offset by mix-adjusted rate increases. The Non-dating revenue increase of $59.4 million, or 235.0%, was driven by the acquisition of The Princeton Review. 70 Table of Conteda Cost of revenue (exclusive of depreciation) Nine months ended September 30, 2014 2015 change Cost of revenue Percentage of revenue (dollars in thousands) $ 82,079 $ 131.118 59.7% 12.6% 17.4% Cost of revenue increased $49.0 million, or 59.7%. in 2015 versus 2014. Dating cost of revenue increased $28.5 million, or 41.9%. meaningfully more than growth in revenue, driven primarily by a significant increase in in-app purchase fees given that our native mobile apps were largely introduced in the second quarter of 2014, as well as higher hosting fees driven by growth in users and product features. Non-dating cost of revenue increased $20.5 million, or 147.4%, driven by the acquisition of The Princeton Review, for which cost of revenue represents a meaningfully larger percentage of revenue than in Dating. Selling and marketing expense Nine months ende