Michigan, as I've noted in the past, presents unusually detailed and informative placement data on its website, which permits one to get a detailed picture of how the job market looks coming out of a top department. I focus on Michigan only because the data is so thorough and because I have a good handle on where the graduates listed are teaching now (though the site is fairly up-to-date). Michigan was also clearly a "top" department during the period I'm going to examine--uncontroversially top ten, perhaps top five for much of this time. I have made a casual, but not systematic, study of the competition, and my conclusion is that only two top departments (Princeton and MIT) have, for this period, significantly better placement records than Michigan. NYU and Rutgers seem to be developing stronger records at present.
There were 46 graduates who earned the PhD between 1990 and 2000 at Michigan. Of these, 9 do not presently have academic positions, and 3 others have non tenure-stream positions. In other words, 1 out of 5 graduates of a top PhD program are not in an academic position, and about 1 out of 4 are either out of academia or in a non tenure-stream position. That's the sobering news.
Now the more hopeful news. About 41% of the graduates (19 philosophers) have tenure-stream (in many cases, now tenured) positions in PhD-granting departments. (16 philosophers, about 35%, have tenure-stream positions in PGR-ranked PhD or MA-granting departments.) About 9% of the graduates have jobs in excellent liberal arts colleges. 13% of the graduates during this period now teach in "top 20" philosophy departments, while 3 graduates (about 7%) teach at "top ten" departments.
Depending exactly on how one assesses various jobs, it's fair to say that 60% or more of the graduates during this period have excellent academic positions--at research universities or departments with a strong research orientation, or very good colleges, places with good students and reasonable teaching loads.
Remember that these statistics are drawn strictly from those who completed the PhD (that's part of what makes the first set of figures so sobering). Attrition rates vary quite a bit is my impression. I started at Michigan in the fall of 1988, and of my class of nine, two never finished the degree. But next year's class had a much higher attrition rate, over 50%. But I am inclined to think the more meaningful stats concern those who finished the program. It is one thing to spend a couple of years in grad school and then move on to something else. It's another thing to invest six or seven or eight years in earning a PhD. Students quite reasonably want to know: what happens to me after all that effort?
UPDATE: A couple of folks, in correspondence, suggested that perhaps those no longer in academia left voluntarily to do something they preferred. In most (perhaps all) of these cases, the graduates were seeking academic employment, and failed to secure it. What I am less sure about is whether or not some of these individuals had a "floor" for the kind of academic employment they would accept, such that they would prefer careers outside the academy to certain kinds of jobs within the academy.