Correlation matrix based on common values

Hello, first of all let me say I'm a newbie so any help is appreciated.

I have the following sample data set:

SALES REP, SALES ORDER NUMBER

Anthony C, 1234

Johnny P, 5678

Crystal M, 9283

Johnny P, 9283

I want to create a matrix that would have the the SALES REP as both column and rows and would list the number of unique SALES ORDER NUMBERs in each box. For the data above, the result should look like this:

Anybody has any ideas? I've done a search on the forums but cannot seem to find something similar.

Thanks,

Jose