From what I remember from high school typing class, GWPM or Gross Words per Minute is the count of how many words you can type in a minute. In our class, there was also NWPM or Net Words per Minute, meaning the number of words you can type *correctly* within a span of a minute.
For instance, I typed this in 20-seconds:
QUOTE
The quick brown fox jumpd over the lazy dog.
That's 9 words in 20 seconds or an estimated 27 GWPM.
But I got "jumped" typed wrong, so that's 8 correct words in 20 seconds or an estimated 24 NWPM.
In most typing classes, I think the NWPM is used to stand for WPM and is a better way to gauge how fast you type. After all, if students can just tyep owt evrything fsst enougj, youd get somthing loke tyis. Definitely better to see a high NWPM. *Nods, nods*
70 WPM? I think that's pretty fast... as long as you're not just typing out the word "a" ;). Also, since you mentioned it's GWPM, I hope your typing's not full of errors. :p
Personally, I think I can only type out 40 words per minute at max speed. But then, I have this habit of hitting backspace whenever I see a mistake I made, so it slows me down a bit (though my GWPM and NWPM becomes equal after :D).