if you want to get technical, any substance that changes your mental state is a "drug" and since that includes things like tylenol, then i think it's safe to say that almost everyone here uses "drugs" to some effect.
if you want to narrow the term "drugs" down to things like alcohol, cigarettes, marijuana, shrooms, acid etc. then the percentage of people in this forum that use "drugs" is lowered, but not significantly.
however as a general rule, when people say the word "drugs" they're conciously leaving out alcohol and cigarettes due to the large quantity of people that use them regularly, so if you cut those two out of the group then the percentage is once again lowered, but not significantly.
one of the biggest issues in american society today is the use of "illegal substances," but if you sit down and look at it, the only reason why most of them remain "illegal" is because of the lack of consistency in the way our laws are created. if you want to use the arguement that these illegal substances are more dangerous than things like alcohol, cigarettes, or over the counter/perscription medication, go talk to a scientist. you'll discover something that's completely logical but has been blatantly ignored. any substance that is used in excess becomes extremely dangerous, even cigarettes.
so really the questions that need to be asked are "what is the difference between legal and illegal substances?" and "why are they still categorized in the manner in which they are?"