How many "This domain is for sale" page on the Internet?

[pixelman]

Many good domain names are gone.
But when you checked the domain, you would find a "This domain is for sale" page in many cases.

Anyone has the statistics on the number of such page?
Curiuos...

 

[DotComster]

Only %5 of domains are acutaly used - the rest are as you said "for sale" ;(