I don’t doubt those numbers, but many, many people come back to the church in their early thirties after they are married and perhaps have children.
And they stay. It may be just a season of life issue.
What would the numbers be if there was no Sunday School? I would say, even higher. Like stated previously, some parents come back to church when their kids get involved with a program. That would kind of point to Sunday School being important. It plants a seed in the parents head that makes them want that for their kid (even if the parent has fell away from the church. If the parents didn’t fall away, then it’s a moot point b/c they obviously know the importance of Sunday School).