From Pew Research's selected data:
Daily Internet Activities: Using the internet, email and search are top daily tasks Activities on the web: notice that (41%) read blogs, more importantly: Research a product or service before buying it (78%) From 20% - 70% adoption of Internet usage from 1996-2006 (PDF) Who uses the internet: Stats by age, sex, race, income and education. Looks like most Americans do, although there's a significant dip in those with low advanced education and low income.
Please note that Pew's research is only American centric. I've some other data on global usage, and quite a few posts tagged "Web Usage" This data is helpful, I'm actually blogging it really more for my own personal archiving purposes, as I sometimes have to pull these stats up for our clients. I can recall when I was asked; "so how many people really read blogs", this would have been helpful.
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