The American Institute of Architects (AIA) has reported that the Architecture Billings Index (ABI) concluded 2015 in positive terrain. Despite a few instances where the demand for design services decreased from a month-to-month basis in 2015, the ABI was positive for eight out of the twelve months of the year.

December’s ABI score was reported as 50.9, up from the reading of 49.3 in the previous month. This reflects a slight increase in design services, since any score above 50 indicates an increase in billings. The new projects inquiry index was 60.2, up from November’s score of 58.6. As a foremost economic indicator of construction activity, the ABI reflects the approximate nine to twelve month lead-time that occurs between architecture billings and construction spending.

“As has been the case for the past several years, there continues to be a mix of business conditions that architecture firms are experiencing,” said AIA Chief Economist Kermit Baker, Hon. AIA in statement. “Overall, however, ABI scores for 2015 averaged just below the strong showing in 2014, which points to another healthy year for construction this year.”

Significant ABI highlights from December include the regional averages of 53.7 in the West, 53.3 in the South, 46.7 in the Northeast, and 46.1 in the Midwest.

The sector index breakdown reports a multi-family residential score of 52.9, an institutional score of 52.2, a commercial / industrial reading of 47.3, and a mixed practice score of 46.5. The design contracts index for December was reported as 51.0.