Not a technological person here, but I think proximity to a test server affects the results.

Unfortunately, there isn't a "close" server to me in Central Bumf*ck, VA. Ashburn in VA and Greensboro, NC yield similar results ~10Mb/s, but the one in WV yields a fastest upload @ ~7,2 Mb/s. I'm sure it'd be faster if I wasn't using wireless.