Completing the game will net you a 76 percent rating on the leaderboards. You get 2 percent for each achievement, making a total of 22 percent (if you already have the achievements this is included in the bundle). You are given another 2 percent if it is a second play through, or if you are playing a chapter having already completed the game. Finally, you get 1 percent with each secret egg.
As you mathematicians will have realised, the total adds up to 100 percent not including the secret eggs. That means that if you have already completed the game with all achievements, you are guaranteed to get 100 percent on your next playthrough.
The secret eggs add up to 11 percent, meaning the best you can get on the leaderboards is 111 percent!