Percentages can be absolutely brilliant. They can remove a ton of distractions and questions and give you a strong indication of some numbers. For example, it is handy to know that 30% of your visitors are browsing using Internet Explorer and 4% are using Opera. This is probably easier to grasp as a percentage rather than being presented with a series of big numbers against each browser.
Sometimes, though, you need to be careful with the percentage. It can make huge numbers sound insignificant.
Sometimes you need to get back to the real numbers to really understand a problem.
Note on Numbers
This is 2% of the estimated 108,096,800 people in the US with Internet access.