A November 21, 2006 entry on the Nictotine News blog mentions an observation from ACSH's Dr. Gilbert Ross:
From the American Council on Science and Health:
Although almost half of all smokers had a routine medical checkup in 2003, only 63.6% of those were counseled by a physician to stop smoking -- and this is an improvement from 2000's rate of 57%!
Approximately three quarters of smokers want to quit. Each year, around half make the effort to try. Unfortunately, given the current state of cessation aids, only a minority succeed. But the success rate -- the rate of long-term abstinence -- goes up with each and every attempt. And one of the most potent stimuli for a person to quit is being advised to do so by a physician.