I've never seen WordPress publish statistics about that for all blogs. You can check out any blog's traffic at Quantcast.
I'm only guessing, but of the 30 million blogs hosted here at WordPress.com, most probably don't get more than a few hundred pageviews per day -- if that. On the other hand, there are undoubtedly many that get several thousand per day, or more.
Every blog is different. Different subjects, different motives, different talents. What other blogs are doing shouldn't affect how you think about your own blog. If you like what you're doing, that's really all that matters.
If you're interested in increasing your traffic, there are thousands of threads on that topic. A topic search will give you several of them. Just use the search box above.