Average for multiple columns of data

Hi,

I am looking to calculate the averages for data that looks like this:
Method Problem size Nodes expanded
BFS 1 6
BFS 1 6
BFS 1 10
BFS 1 10
BFS 2 21
BFS 2 39
DFS 1 146855
DFS 1 148596
DFS 1 1191255
DFS 2 12
DFS 2 14

I have allot of data and am unsure of the best way to do this. Was wondering if any body knew of any easy way to do this, thanks.

you're going to have to be a bit more specific, do you want averages of each method? average of each column or the average across all the numbers together?

Sorry, i'm looking for average nodes expanded for each problem size, for each search method so the final output would be say:

BFS
Problem Size Average Nodes Expanded
1 7
2 30

thanks for your help.