Personally, I rarely publish my deals to Publishers Marketplace. The editors often do, though. I'm more likely to mention it on my blog, but even then I often leave out mention of foreign deals. My preference is to publish when I have a signed contract, not a verbal deal. Since months can go by between the two, I just lose track of whether or not the editor posted on PM and don't bother. My clients know I made the deal for them and that's what matters.
A better way to judge may be to go to that agent's website and see what kind of books they rep, which authors they rep, etc.
As for "how often," I'm not sure that's a good criteria by which to judge. I have a client for whom I have done three deals in about a decade. One was a five-book deal, one was a three-book deal, and one was a six-book deal. And each of those deals took months to hammer out (the last took over a year). So is three deals in a decade too few, or just right, for this client?
Z