The answer to this question is undoubtedly "virutally everyone". 

This claim must, however, be qualified by the observation that some are more readily hypotisable than others and that it will also depend on ones willingness to be hypnotised at the time.  This willingness will itself depend upon a number of factors, not lease of which will be the strength of the persons particular need and their trust and confidence in the therapist concerned.  A corollary to this question is "what level of trance is required in order to achieve a beneficial outcome?"  Although there remains some disagreement over the answer, most researchers concur that the actual level or depth of trance obtained does not relate to the beneficial results that might be obtained. 

In practice , this means that even where a person feels that they have not been hypnotised, given time (and this is an important factor) the desired outcome of therapy might yet materialise.  This matter of time is especially important in our current society, which has, in many respects been coerced into believing that gratification of every desire should be instantaneous.

Hypnotherapy can be extraordinarily effective but it is not magic! However if the right ingredients are present, if the time is right and if a suitable practitioner can be found with whom the client is willing to work, then all their realistic goals are achievable.

** Information provided by the GHR , the hynotherapy regulating body.