What percentage of US companies filter their employee's access to the web?

Question

I need a reference to a supporting study, not just a personal guess.

Answer 1

The word "filter" itself is vague.
Most companies have spam-protection, which is a type of filtering.
On that basis, likely 99% filter the internet is some way.

But I know what you are really asking, and I don't know any good resource to point you toward.

Some very interesting facts are found at:
http://www.netpart.com/global/en/PressRoom/MediaCenter/Research/InternetStatistics/
http://www.csoonline.com/metrics/viewmetric.cfm?id=443
http://myweb.cwpost.liu.edu/paievoli/finals/504Projects/Prj1/bridget-filteressay.htm

And a more research-oriented directory is found at:
http://whitepaper.samag.com/cmpsamag/search/browse/1765/1765.jsp

Hope this helps.

Respectfully,
TimF

Answer 2

50%