I implemented a loop with up to 100fps and can not spend more than 63fps.
What I believe is that the thread that runs the method of drawing opengl has a speed limit. "( @Override public void onDrawFrame(GL10 gl) )"
It depends on whether or not your rendering context has vertical sync enabled. Most LCD devices refresh at 60hz, and it may be waiting for the next refresh to call onDrawFrame(). That's one reason you'd be seeing that number.
The other possibility is that your draw is just taking long enough that it can't run any faster.