Missions: All Completed
Download "COD BO III (100% Save Game) [PC]" and extract the "players" folder or the file inside it to:
C:\Program Files (x86)\Steam\steamapps\common\call of duty black ops III\players
C:\Program Files (x86)\Activision\Call of Duty Black Ops 3\players
Don't Forget to Backup your own Save Game.