This is impossible to answer and an academic question as what you really want to know is what YOUR chances are -- not what odds are that the average 2 time convicted criminal would win parole after serving half his sentence.That would require knowledge as to what the crime was, whether there were special circumstances, what the judge said at sentencing, what the sentence recommendation was, what the law and custom is in your state, what your conduct in prison has been, what steps you have taken to rehabilitate yourself, whether you have been contrite and appreciate the harm you did, whether you have learned a skill you can use and gain employment outside, whether there is a mechanism in place that will almost assure that if you are released you will not revert to criminal conduct,  how crowded the prisons are in your state, etc. etc.