<P> In the 1930s, Edgar Snow commented in Red Star Over China that the Communist forces in the Chinese Civil War had a "passion for the English game of table tennis" which he found "bizarre". On the other hand, the popularity of the sport waned in 1930s Soviet Union, partly because of the promotion of team and military sports, and partly because of a theory that the game had adverse health effects . </P> <P> In the 1950s, paddles that used a rubber sheet combined with an underlying sponge layer changed the game dramatically, introducing greater spin and speed . These were introduced to Britain by sports goods manufacturer S.W. Hancock Ltd . The use of speed glue increased the spin and speed even further, resulting in changes to the equipment to "slow the game down". Table tennis was introduced as an Olympic sport at the Olympics in 1988 . </P> <P> After the 2000 Olympics in Sydney, the ITTF instituted several rule changes that were aimed at making table tennis more viable as a televised spectator sport . First, the older 38 mm (1.50 in) balls were officially replaced by 40 mm (1.57 in) balls in October 2000 . This increased the ball's air resistance and effectively slowed down the game . By that time, players had begun increasing the thickness of the fast sponge layer on their paddles, which made the game excessively fast and difficult to watch on television . A few months later, the ITTF changed from a 21 - point to an 11 - point scoring system (and the serve rotation was reduced from five points to two), effective in September 2001 . This was intended to make games more fast - paced and exciting . The ITTF also changed the rules on service to prevent a player from hiding the ball during service, in order to increase the average length of rallies and to reduce the server's advantage, effective in 2002 . For the opponent to have time to realize a serve is taking place, the ball must be tossed a minimum of 16 cm in the air . The ITTF states that all events after July 2014 are played with a new poly material ball . </P> <P> The international rules specify that the game is played with a sphere having a mass of 2.7 grams (0.095 oz) and a diameter of 40 millimetres (1.57 in). The rules say that the ball shall bounce up 24--26 cm (9.4--10.2 in) when dropped from a height of 30.5 cm (12.0 in) onto a standard steel block thereby having a coefficient of restitution of 0.89 to 0.92 . balls are now made of a polymer instead of celluloid as of 2015, colored white or orange, with a matte finish . The choice of ball color is made according to the table color and its surroundings . For example, a white ball is easier to see on a green or blue table than it is on a grey table . Manufacturers often indicate the quality of the ball with a star rating system, usually from one to three, three being the highest grade . As this system is not standard across manufacturers, the only way a ball may be used in official competition is upon ITTF approval (the ITTF approval can be seen printed on the ball). </P>

When did table tennis change from 21 to 11