The average adult reads at 300 WPM, while comprehending what it is they're reading. Do you read faster or slower than the average?
You can take a short test here: http://www.readingsoft.com/
I got 480 WPM on my first try, then I realized I could answer just 3-4 of the comprehension questions. I did it again with full comprehension and I read at 320 WPM, and it's slow for someone who reads a lot but I don't really care. I like sounding out the words in my head (but only when I'm reading books, not articles) because it makes the experience more enjoyable. I know I could improve if I stopped auditory reading (sounding out the words in my head) but I'd rather not.