New York - A trio of market research firms covering the video game industry announced on Thursday that they will combine their data to offer the Top Global Markets Report, the first to integrate video game sales data across the U.S., U.K. and Japan. New York-based NPD Group, U.K.-based GfK Chart-Track Limited and Japan's Enterbrain said they plan to issue the joint report monthly. The five top-selling titles year-to-date across the three territories, according to the report, are "Grand Theft Auto IV," "Super Smash Bros: Brawl," "Mario Kart Wii," "Wii Fit" and "Guitar Hero III: Legends of Rock."