There is no average pay for this industry. There are guidelines available online to help you do the math for what's right for you.
When you consider that the industry is global so that means many different countries with different currencies, and then there's the education levels, background knowledge and experiences (some have only 5 years office/admin experience and others have over 40), the type of services VAs are providing - some are doing wordprocessing, some transcriptions, bookkeeping, internet research - there's no way you could charge the same hourly rate for each item. And of those who do transcription work, some charge by the typed hour, some by the audio hour, some by the audio minute and some by the page.
It's soon easy to see why there could never be an 'average' for charging out your services. If you look locally to where you live as to what the annual income would be for what you do in the corporate world and then work backwards with Nina's tool mentioned below, then that will help steer you closer to the mark.
Nina Feldman has a spreadsheet that will assist you at
http://www.ninafeldman.com/resources.htm#ptools. I also have a similar exercise in a book I wrote for the industry a few years ago and that works well too.