Some open-source math:
round( OSProjectsThatWork / TotalOSProjects ) == 0;
round( OSProjectsThatWork / TotalOSProjects ) == 0;
By "work" I mean work well out of the box, have all essential functionality, can be configured easily w/o an 800-page book, do what's necessary w/o modification.
And let's add to that, can be installed in less than 3 days and have no dependencies on things that, themselves, take 3 days to install.