Trying again: Can any speech pathologists explain and show the data they use when why they say 1 percent of the population stutters?

Trying again: Can any speech pathologists explain and show the data they use when why they say 1 percent of the population stutters? Nothing to argue about. I just want the academic research and information. I also want to know if this also includes young children that stutter. That is pretty common. What is the percent of the population that continues having stuttering speech disorder into adulthood?