Background: AKB48 (pronounced A.K.B. Forty-eight) are a Japanese idol girl group named after the Akihabara (Akiba for short) area in Tokyo, where the group's theater is located. The group has expanded since then to include over 130 members as of December 2015, aged from their early teens to their mid-20s. AKB48's producer, Yasushi Akimoto, wanted to form a girl group with its own theater (unlike pop groups performing occasional concerts and seen on television) and performing daily so fans could always see them live. This "idols you can meet" concept includes teams which can rotate performances and perform simultaneously at several events and "handshake" events, where fans can meet group members.
Context: In October 2006 AKB48 announced auditions for Team B, and 13 girls were chosen out of 12,828 applicants in December. The group's first DefStar Records single, "Aitakatta", was recorded by 20 members of Teams A and K and released on October 25. It debuted at number 12 on the Oricon weekly singles chart, selling 25,544 copies in its first six weeks, and remained on the chart for a total of 65 weeks. On November 3-4 AKB48 performed its first concert, "AKB48 First Concert: Aitakatta ~Hashira wa Nai ze!~" at Nippon Seinenkan in Shinjuku. The group performed "Aitakatta" on the New Year's Eve TV program 58th NHK Kohaku Uta Gassen as a part of the "Nihon ga Hokoru Saisentan! Special Medley". At 43 members, the group set a program record for the most people in one group onstage simultaneously. AKB48 made its first lineup change in December, transferring Kazumi Urano, Shiho Watanabe and Natsumi Hirajima from Team A to Team B as supporting members.  AKB48's second major-label single, "Seifuku ga Jama o Suru", was released on January 31, 2007 and debuted at number seven on the Oricon Top 10 chart. Its music video and lyrics hinted at the subject of enjo kosai (compensated dating, remotely related to escort services outside Japan), triggering controversy and negative reviews. On March 18 AKB48 released "Keibetsu Shiteita Aijo"; debuting at number eight on the Oricon chart, it dropped to number 98 in its second week. The group's second concert, "AKB48 Haru no Chotto dake Zenkoku Tour ~Madamada daze AKB48!~" on March 10, had poor ticket sales.  In April 2007 AKB48 posted its Team B roster on its website, with five fewer members than originally announced; for the first time, its membership numbered 48. The group's fourth single, "Bingo!", was released on July 18. AKB48's sixth single, "Yuhi o Miteiru ka?", was released on Halloween 2007 and sold 18,429 copies (the least of all the group's singles).
Question: How many members do they have in the group?

Answer: