Ken Yasumoto-Nicolson of What Japan Thinks has posted results of a Goo Ranking survey of manga readers in Japan:
The poll was conducted by goo Research monitor group, with over half of the respondents in their 30s and 40s. Also, over 60% were female.
After reading this poll I find myself wondering what series will be ending soon?
At the same time, it is good to know that future researchers will be able to test these poll results against the publications themselves, as we build up a collection of manga magazines at Ohio State! (See the new collection development policy for details.)