Before 1973, there were no computer-based rankings based on the points players obtained for achieving a certain level of performance in particular tournaments, but there were journalists or officials (on their personal behalf) or promoters or players themselves who listed their own subjective annual rankings. However, in 1946, 1959, 1960 and 1964-1968 there were point ranking systems and seeding lists applied to professional series of tournaments involving all of the best pros. In 1946, 1959 and 1960 there were also World Professional Championship tours with a small number of pros, which did not produce point rankings. The winner of the 1946, 1959 and 1960 World Professional Championship Tours were described as "world champion" in many reports, as distinct from the point series "world No. 1". In 1963, the ITPTA World Championship Tour produced an official ranking order for the contract professionals. In some years, however, only a small number of journalists or players released rankings at the end of the tennis year. For these years, retrospective rankings done by tennis historians or sports statisticians many years after the tennis year ended (i.e. in the 2000s for a year in the 1950s) are considered by the editors in their determination of which players should be ranked No. 1 and No. 2. There are no available contemporary or retrospective professional rankings for 1947 or 1957, but only amateur rankings for those years.