Aside from the statistics inthe new YB there are also a couple of cases of it promoting child baptism.
In the section about the young remembering their grand creator in Georiga you will find this...
https://www.jw.org/en/publications/books/2017-yearbook/georgia/youth-remember-grand-creator/
In support of parental training, elders try to involve young ones in congregation activities as early as possible. Nestori, who was baptized when he was 11 years old, states: “The elders gave me various small assignments from a very early age. This has helped me feel that I’m really part of the congregation.”
In the section in JW Broadcasting you will find this...
Kodi, from England, says: “Thanks for all the time and effort you put into making jw.org, JW Broadcasting, and the Caleb and Sophia videos. Thank you for making the Bible easier to understand. I was baptized when I was eight. When I’m a bit older, I’m going to volunteer to help build Kingdom Halls! And I would like to work at Bethel. I’m nine now, so I’ve not got long to go.”