History
The London Daily Telegraph began unofficially ranking male players, at the end of the tennis season, in 1914. Only amateur players were eligible for ranking until 1968, when the major tournaments were opened to professionals.
In 1973, the Association of Tennis Professionals developed its own rating system, which is updated weekly and used for seeding players in tournaments.
The listing here shows the player ranked first in the world by the ATP system at the end of the year.