What percentage of health decisions can be evidence based?

In 1980 in the Annals of Internal Medicine, DS Brody claimed that "If medical practice were based on truly objective scientific data, it would be very easy to make defendable decisions without any fear of self-reproach. Unfortunately, medicine is not an accomplished scienceŠthere are tremendous gaps in scientific knowledge. Most of a physician's daily decisions do not involve situations that have been tested in double-blind, randomized trialsŠfor [estimated] 90% of medical conditions there is either no specific remedy or effectiveness of treatment is unknown" (p. 720)

Does anyone happen to know of a more current reference (since 2000) that gives an updated estimate of the percentage of medical conditions for which there is no specific remedy or for which the effectiveness of treatments is unknown? Is it still 90%, or have we made some progress since 1980? A published estimate from the peer-reviewed literature would be most helpful, but I'd also be interested in people's own estimates, based on their familiarity with the literature.