I think the numbers are quite accurate. If they wanted to fix them they would be reducing the number of the memorial partakers. In all the congregations around me they have had fairly consistent numbers at meetings for many years, which is in line with the number of Aust publishers showing little change over 10 years.
What the numbers do not show is how many of the publishers actually believe in the Watchtower Society, or how many do the hours that they report. I am sure as I did for many years that there are a growing number that report just to keep the elders off their back.
I would love to see a Standard Deviation showing what the median hours are and how many publishers just report 1 hour.