Had you RTFA, you would have seen Weir's data on said mirror sites (SourceForge provides AOO's mirror service, and rather than being "antagonistic to reporting per-product statistics" it is downright open about them, providing a query API).
LibreOffice and OpenOffice clash over user numbers (OStatic)
Posted Nov 15, 2012 19:08 UTC (Thu) by JanC_ (guest, #34940)
[Link]
Other sites (many of the well-known mirror sites) also mirror AOO & LibO, often without providing (public) statistics. It's simply impossible to get a correct number of downloads/installs that way.