Here is an excerpt from a survey -

"Four out of 10 adults who stutter have been denied a job or promotion and 82 percent of children who stutter have been bullied or teased, according to a new survey by the National Stuttering Association. People who stutter make up about 1 percent of the population."

But there is good news as well -

"People who participate in stuttering support groups report fewer negative effects of stuttering and more successful speech therapy than those who do not. Support groups help people improve their self-confidence and develop positive attitudes about speaking and stuttering."

and

"Speech therapies that change attitudes toward speaking and stuttering are more successful than therapies that focus on speech mechanics."

You can read the full article here -

Survey: Speech Therapy Helps, But People Who Stutter Suffer Discrimination