Downtown office vacancies fell, a survey shows.

The downtown office vacancies declined slightly during the first quarter of 1987 to 16.3%, marking the sixth-straight quarter in which the national rate has hovered in the fairly narrow range of 16.1% to 16.7%, a Coldwell Banker Commercial Real Estate Services survey shows. National suburban office vacancies, on the other hand, increased to 23.9%, a rise of 0.1% from the last quarter of 1986, setting a record high. The survey covers 42 major office markets across the country. Several markets reflected especially strong suburban office absorption in the face of high levels of new construction completed during the quarter. In California, these included Sacramento, down 0.3% to 24.5%; Orange County, off 0.5% to 22.8%; Oakland, down 0.4% to 31%, and Los Angeles County, off 0.4% to 16.9%.