Someone said $250 per publisher, I don't know what country that calculation came from, but that is far from reality.
In our congregation in the USA, and keep in mind we are not an English speaking congregation, the average is as follows:
Donations to the congregation (for operating costs, bills, etc...) = $8 per publisher
Donations to the World Wide Work = $2.50 per publisher
Donations to the Kingdom Hall Fund = $0.00 per publisher
These are actual averages for 2004.
I also served in third-world country that has over 100k publishers, and the branch would only average about $20 per congregation (after monterary conversion into dollars) per month. In order to cover costs, they would turn over bills, expenses, etc. to the Watchtower in Brooklyn.
>edited to add that the above averages are based on "per month" donations. After rereading the original post, the question was asking for "per year" average.