What percentage of the population did the proles make up? What methods are used to easily keep the proles in control?

The Proles represent 85% of the population. The Proles are considered mindless animals by the Outer Party. The Inner Party is not concerned with them as long as they wallow in their own ignorance. The Inner Party controls them by feeding them things like porn, the lottery and cheap alcohol. As long as the Proles are wrapped up in their superficial lives, they won't question politics. Check out Book 1, Chapter 7.