Determining average value

[N R A]

Is there a simple program available that will allow me to determine the 
average value for a raster data set. 

I'm basically using the 'r.water.outlet' program to generate the 
catchment area, then using that as a mask on various catchment 
characteristics data sets - such as potential evaporation, SAAR, etc. 
I've tried 'r.stats -a ' but that gives a breakdown by each value. I can 
load the values into a spreadsheet and calculate an average but I'd hope 
there was a way to do it in GRASS. I've looked at the 'r.average' but 
don't quite understand it - the output is a raster map, what I want is a 
single value, e.g. the average potential evaporation.

Cheers,

Steve Culshaw
NRA North West
e-mail : nra at cix.compulink.co.uk (use this for general usage)
or         sculshaw at cix.compulink.co.uk (Private - only checked at best 
biweekly)