Depends completely on what your definition of virus is. There are trojans for the Mac but no worms or other types of self-replicating viruses.
Also, there is no way there are 200,000+ viruses for Windows. Several variants of the same virus will get counted separately by the anti-virus companies as it makes their products seem more necessary. In reality in many cases the same AV definition will catch all of those variants so they could be classed as just one.