What percent of birds are flightless?

I am taking the liberty of presuming that we are talking about real, living birds which are of an intrinsically flightless species (as opposed to undeveloped chicks or injured birds.)

There are about 11,000 known species of birds including 18 species of penguins, 4 of emus & cassowaries, 2 rheas, 1 ostriich and 3 kiwis. As far as I know, apart from these 28 species, almost all others are capable of flight (even if not very far, like chickens.)
I also see that the flightless species are large birds that don't have anywhere near the population sizes of the more common flying species.
My estimate would therefore be less than 1% of all birds being of flightless species.

[Feb 15 04 7:24 PM] gmackematix writes:

I did mean to say that the flightless species are "mostly" large birds. I don't wish to offend any little kiwis out there.