customer service call centers, increased $36.6 million due to our growing member base.

Marketing expenses increased primarily due to an increase in advertising and public relations spending.

Our Domestic streaming segment had a contribution margin of 27% for the year ended December 31, 2014, which increased as compared to the contribution margin of 23% for the year ended December 31, 2013 due to growth in paid memberships and revenue, which continued to outpace content and marketing spending. The decrease in net membership additions in the year ended December 31, 2014 as compared to the year ended December 31, 2013 is a natural progression of our large domestic market as we grow. We expect to continue to increase domestic contribution margins over the next several years even with lower membership growth.

The increase in our domestic streaming revenues was due to the 26% growth in the average number of paid memberships. New member additions and revenue related to $11.99 membership plans that were introduced in the second quarter of 2013 were not material for the year ended December 31, 2013.

The increase in domestic streaming cost of revenues was primarily due to the $226.3 million increase in content expenses resulting from continued investments in existing and new streaming content including more exclusive and original programming. In addition, streaming delivery expenses increased by $31.7 million and other costs, such as payment processing fees and customer service call centers, increased $34.8 million due to our growing member base.

Marketing expenses increased primarily due to an increase in advertising partially offset by a decrease in payments to affiliates in the U.S.

Our Domestic streaming segment had a contribution margin of 23% for the year ended December 31, 2013, which increased as compared to the contribution margin of 17% for the year ended December 31, 2012, as a result of growing memberships and revenue faster than content and marketing spending.



International Streaming Segment



In the International streaming segment, we derive revenues from monthly membership fees for services consisting solely of streaming content offered through a membership plan. We launched our streaming service in Canada in September 2010 and have continuously expanded our services internationally with launches in Latin America in September 2011, the U.K. and Ireland in January 2012, Finland, Denmark, Sweden and Norway in October 2012, the Netherlands in September 2013, and Germany, Austria, Switzerland, France, Belgium and Luxembourg in September 2014. In the first quarter of 2015, we expect to launch our service in Australia and New Zealand. Later in the year, we expect to launch additional major countries, in keeping with our global strategy.

The increase in our international revenues was primarily due to the 82% growth in the average number of paid international memberships as well as the 1% increase in average monthly revenue per paying member resulting from the price increase on our most popular streaming plan and the introduction of the premium plan, offset partially by the impact of exchange rate fluctuations. Average paid