As the saying goes, there are lies, damned lies, and statistics. It is necessary to
   take any official Chinese statistics about the speaking of Mandarin with a great
   deal of salt, firstly because all governments lie when it suits them, and secondly,
   because in a totalitarian society respondents to official surveys tend to give the
   answers which they think the government wants. To illustrate, I have known people,
   mainly Cantonese speaking, from mainland China who have been through the school
   system, to the finish of high school at least, who could hardly speak Mandarin, their
   teachers and inspectors having been in collusion to hide the fact that they, the
   teachers, were incompetent to teach the language, and that the pupils had no
   interest in learning it. I have no direct evidence, but I suspect that the further one
   might go from Beijing, the more likely this situation is to occur. Having said that,
   i don't doubt that, fudged numbers aside, Mandarin is the language spoken more than
   any other. The written language question is tricky too, since the Communists
   'simplified' the characters, and older people and those who learn their characters
   in some overseas Chinese schools, find the new characters hard to read. This also
   applies to the Chinese characters which the Japanese use for some purposes, they
   are old style too.
                         Don.