John Florian has published the results of the VoiceOverXtra survey of your peers regarding volume of work and income. This survey was conducted online in October of 2008 and is based on responses from 204 voice actors, with no correlation kept between the answers and the respondents.
A couple of things I thought were interesting. Just about exactly half of the voice actors responding have been at their craft for 10 years or more, more than half work at voice acting full-time and 60% are non-union with another 8% who are dues-paying non-members (Financial Core).