Complete all of the following to get 100% completion:

GAME COMPLETION PERCENTAGE - HOW TO EARN
68% - Complete all 90 story and procedural missions.
10% - Get all friends special abilities and complete all of their activities(excluding  dwayne and roman).
5% - Beat friends or computers at every activity.
5% - Find all random characters and complete their missions.
2.5% - Collect all 200 pigeons.
2.5% - Complete all 20 vigilante crimes.
2.5% - Complete all 50 stunt jumps.
2.5% - Kill all 30 people on the list.
2% - Complete all 30 vehicle thefts.