Research company DoHouse conducted an online survey about the rating of TV anime series. 23,388 respondents answered the number of TV anime programs they watch in March 2010. (The respondents were selected from 2.6 million registered users in order to avoid bias and maneuvering.)
Bar Graph of the result (y axis: age, x axis: percentage)
The name recognition of female seiyu was significantly higher than male seiyu. The highest recognition of Mizuki Nana can be attributed to her appearance in the popular music show Kohaku Uta Gassen last year.
Note: This is for the first time that this company conducted an anime (otaku-culture) related survey. Being an online research is the only possible bias. example of the topics in the past: eating habits, traditional events, hay fever etc.