I am looking for information regarding the annual number of traffic
signals installed in the Bay Area broken down by county. I am most
interested in data for San Francisco and Alameda counties. I am not so
concerned with the number of currently installed lights as I am the
number of lights that are installed each year. I need the data for as
far back as it is available.

If an answer is not available, information regarding where might I go
or who might I contact in order to obtain this data would suffice.
Please reference any sources used.