I think one really decent way is to leverage excelcustom reports, and the vulnerabilities.csv.
Excel:tab 1-paste contents of the vulns.csv
excel tab 2-pivot table with the system names as the source. adjacent columns searching "tab 1" for the number of occurences of each system name coupled with the risk level(using the countifs function)-this will give you system name, highs, mediums, lows for each system..and you can easily add another column to total
Excel tab 3 if youre interested in getting affected system counts by for each vuln, you can do another pivot table with the vuln name from "tab 1" as the source. then add a column to count the number of occurrences of each vuln name in "tab 1"
You can do this outside of excel too with scripting, use a custom built app, or there are also some vendor solutions that can help.
I have found the most efficient and modular approach to obtain data from MVM is via writing your own SQL queries. It provides a much simpler facility for dynamically pulling the data you want - I do it in VBA so results come straight into Excel formatted however I desire.If you want reporting customized to your needs read the database schema and starting writing SQL queries !