Re: Counting is not so easy.
Then there are derivatives and rebranding, such as NeoOffice, which can also make difficult to get accurate user base figures for either LibreOffice or Apache OO.
NeoOffice is not a rebrand! NeoOffice has a different ui implementation and is much better integrated into OS X. Read https://www.neooffice.org/neojava/en/faq.php They were the first to port OpenOffice to OS X' Aqua ui.
OpenOffice only released a native OS X version in 2008 (version 3.0), NeoOffice had a working one, with a few bugs in 2003 ...