Hate to tell you, but there isnt rly anything you can do. I have the same thing, by mine is 12%, bcuz of a re constructive surgery when i was 13. You cant change anything, but, and i know it sounds very wrong, but you need to build all teh muscles in your arm up. ALL of them, when they get a little bigger, you will feel them come into play in deceleration. It took me a long time to figure this out, but it worked.
OH, and make sure your stretching ALOT, you dont wana lose range of motion