The Architectural Billings Index (ABI) improved slightly in December, adding 0.1 points for a score of 55.4, extending its gains to three months after a sharp drop earlier in the year. The American Institute of Architects (AIA) notes that December marked the 34th month in a row that the ABI has boasted a score above 50 points—its best performance since its last long-term positive run between April 1998 and December 2000. Any score above 50 indicates growth; the AIA compiles the number based on surveys sent to 300 architecture firms that mainly work in the commercial sector.