first answer: we use SCCM by default to upgrade all Windows computers in our company. BigFix is used for Linux Patching and reporting.
and to clear up what i mean with “historical” data let me give you an example:
on the week before the client upgrade we had patch MS17-004 applicable for 2231 computers, installed on 2101 and outstanding 130.
after the upgrade and cleanup of duplicate machines (as this happens when upgrading via SCCM) we have now: 190 applicable, 145 installed and 45 outstanding.
hope that brings some more background info