from http://uptime.netcraft.com/up/accuracy.html#whichos
Operating systems we can usually work out uptimes for are:
...
* Linux on Intel x86 processor, kernel versions 2.1 to 2.5.24
...
Kernels 2.2.x and 2.4.x are not affected.
Release date of 2.2.x branch - January 1999
Bottom position in Top 50 with max of 1372 days ie. around 3 years and 9 months.
So why there is not at least one Linux box in top 50 ?
f.E.
Kernels 2.2.x used for both "stable" Debian releaes Potato and Woody
http://www.debian.org/releases/potato/
http://www.debian.org/releases/potato/i386/release-notes/ch-whats-new.en.html
http://www.nl.debian.org/releases/woody/i386/release-notes/ch-whats-new.en.html