Community Tip - You can change your system assigned username to something more personal in your community settings. X
How to create a Report(Query Builder) or Webject to list all documents types in Windchill.
Take a look at this document with lots of report ready to use.
I think you should use this report to start.
QML report to count the number of documents by different document types
https://support.ptc.com/appserver/cs/view/solution.jsp?source=subscription&n=CS216381