It's the main page of the survey which the OP conveniently forgot to link
http://store.steampowered.com/hwsurvey
'Unfortunately' those numbers haven't been updated, or the marketshare hasn't changed even 0.1% in the last month.
59.11% Nvidia
32.98% ATI
http://forums.anandtech.com/showpost.php?p=30870082&postcount=82
One month ago the numbers were exactly the same, apparently.
A quick Google search suggests that the numbers were also the same before that... in September.
http://www.nicagamerz.com/foro/threads/30502-Steam-confirma-nvidia-es-favorita-por-un-59.11
"lidera la preferencia de hardware nvidia con un 59.11% , le sigue ati con un 32.98% y el resto ...."
http://www.tomshardware.co.uk/Steam-Catalyst-DirectX-11-ATI-Radeon,news-34252.html
Another link with the same September information.
So, now we've shown that the overall Steam marketshare numbers are bunk, can we completely ignore them?
Or are we assuming that in the last 3 months there hasn't been even a 0.01% change in NV vs ATI?
And just for kicks, here's a post from you Wreckage:
http://forums.anandtech.com/showpost.php?p=30391948&postcount=4
It's those August numbers again, and hey, SAME NUMBERS!
Oop, another one. July numbers.
GUESS WHAT THEY ARE!
http://www.zdnet.com/blog/hardware/steam-hardwaresoftware-survey-july-2010/9427
Same again... shock horror.
So, from July until December, the marketshare was split
NVIDIA = 59.11%
AMD = 32.98%
Intel: 6.22%
Other: 1.69%
Not a single point move from any company in a 6 month period. Amazing.
So, please don't bring up these figures again Wreckage, OK? Not your fault they are useless, but, well, they are useless.