Showing Total Collected in Backend

Hi,

I would like to show the total amount donated in the backend (Joom Donation --> Donors); preferably before the list of records on that page. Eg:

Total Donated: $120.00


The file to be edited appears to be:
administrator/components/com_jdonation/views/donors/tmpl/default.php

Can you provide the code which will allow me to do the above; and where it should go in that file? \

Thanks in advance.