I looked at those stats the last time I was in the Boalt Career Services Office. There were some handouts they gave me (which I do not have with me here in Florida), but most of the info remained at the office, since I only collected information that was pertinent to my career goals and intersts (obviously, those not being public service). If you are particularly interested, you could probably request the info from them.
Just to add some purely anecdotal evidence, I know quite a few classmates of mine who are very public-interest oriented. Many of them were accepted to a number of the top schools, even HLS, and opted to go to Boalt for the JSP program and what they deemed as a better public interest program. Quite honestly, PI was never my cup of tea (mainly because I will have so much debt I will not be able to afford to do it immediately after graduation), so I don't know all the considerations that go into selecting the best school for that area, however, I assume that ANYone who is as passionate as these people are about PI and who would go to a lower-ranked school to pursue a certain area of study would not do so without significant contemplation and adequate research.