This is fairly meaningless, what is classed as a "defect" for example? Not all bugs are equal.

What about comparing code that has similar requirements and has similar numbers of users.

Of course Linux is going to fare well against BS corporate software that was made primarily to satisfy some middle manager.

Likewise open source is going to include a lot of stuff written by college students that nobody actually uses.

Would be more interesting to compare Linux with similar parts of the NT core for example.