We finished the year with record revenues of $68.7 billion. Net earnings nearly equaled an all-time high at more than $4 billion. And our strong operating cash flow of $4 billion maintained healthy liquidity of $11.3 billion.
Taking a closer look at our businesses and our markets:
Last year, Commercial Airplanes delivered 477 airplanes and added 805 new orders, including a 150-plane launch order for our new 737 MAX. We also extended our market-share lead in the twin-aisle segment with a record 200 orders for the 777. Through the first quarter of this year, we booked an additional 412 new orders. This brings our backlog of firm orders to more than 4,000 airplanes valued at a record $308 billion -- an unprecedented foundation for strong and long-lasting growth.
Beyond the numbers, and perhaps most important to our future, we ushered in a new era in commercial aviation -- and retired substantial technical and business risks -- with the certification and first deliveries of the 787 Dreamliner and the new 747-8.
Reaching these historic milestones did not come easily. Game-changing innovation rarely does. But, thanks to the determined ingenuity of our people, we have created two incredible new airplane families that will bring significant value to our customers and to Boeing for many years to come. Both airplanes are performing very well in service, demonstrating high reliability and delivering dramatically improved fuel efficiency and operating economics.
Pilots and passengers alike are welcoming the 787 enthusiastically in each and every city it visits. The 787 is helping to restore the magic of flight to the travel experience, and its dramatically improved environmental footprint plays a major role in that popularity. The Dreamliner is winning critical acclaim, as well, including the premier award for achievements in aerospace -- the 2012 Collier Trophy.
Last year we solidified our product strategy in the single-aisle segment, with the launch of the 737 MAX. Customers quickly signaled their approval with more than 1,000 orders and commitments in its first four months in the marketplace. This new-engine variant of the 737 will be 10 to 12 percent more fuel efficient than today's 737 and will cost less to operate than its competitors.
Shifting for a moment to Boeing Defense, Space & Security:
In 2011, this side of our company also achieved strong operational success --even in the face of severe U.S. defense budget headwinds. We delivered 115 military jets, 131 new and remanufactured helicopters, four satellites and more than 10,500 weapons systems.
Our revenues held steady at $32 billion on continued customer demand for our core offerings and increased international sales, which grew to 24 percent of revenues from 17 percent the year before. We expect international sales for our defense business to reach as high as 30 percent of revenues in the near future -- a roughly four-fold increase from just several years ago.
We also strengthened our market position and growth prospects with an impressive string of strategic wins and new contract awards, including:
- the U.S. Air Force KC-46 tanker program, in which we will design, develop and build 179 next-generation, 767-based tankers -- and maintain our 50-year franchise in this business;
- a U.S. government sale to Saudi Arabia of 84 new F-15s and upgrades to 70 existing ones, which extends production of this advanced fighter to late this decade and positions it well for more international sales;
- the Ground-based Midcourse Defense development and sustainment contract, which preserves our role as prime contractor and keeps us at the forefront of critical missile defense technology;
- And the core rocket stages and the avionics systems for NASA's new Space Launch System, which ensures Boeing a leading role in the future of U.S. space exploration.
Meanwhile, in important growth markets, we continued to expand our capabilities with organic investments -- such as our Phantom Eye and Phantom Ray unmanned systems, and a new Cyber Engagement Center. We also supplemented this activity with some niche acquisitions, including information-solutions provider Solutions Made Simple.
Including new orders booked in the first quarter of this year, Defense, Space & Security's $72 billion backlog is a Boeing record and ranks among the industry's highest.
A longstanding strategic priority for Boeing has been to aggressively grow our services business, and to do so, in part, by leveraging the combined capabilities and synergies of both our major businesses.
Our services teams provide everything to help our customers operate their aircraft more efficiently and effectively throughout the entire lifecycle of the product. They train flight crews and maintainers; provide and provision spares, maintenance and integrated logistical support; and perform modifications and upgrades.
Our competitive edge in services comes through our scale, as you would imagine -- an installed base of 18,000 commercial and military aircraft --and the innovative solutions our technology can provide. Last year, services accounted for nearly 20 percent of total company revenues. And our commercial services segment is forecast to continue growing at double-digit rates.
In this next video, our service business leaders share a few examples of the innovation and value we're bringing to our customers.