I was confused by Cedars' chart too, but couldn't explain it in words until I thought about my own local congregation.
There are older teens that have been publishers for 10+ years, yet have never been baptized. It's fairly common around here for kids to become publishers at a young age, like around 5-7 years old. What this means is that a congregation's publisher count can grow year over year, even with zero baptisms. As long as people keep turning in time, they are counted as publishers. Baptism has nothing to do with it. Theoretically, a person can remain a publisher indefinitely without ever being baptized.
Even when one of these kids gets baptized, the publisher count stays exactly the same. The only time a congregation experiences a publisher decrease is if someone becomes inactive (stops turning in time), is disfellowshipped, dies, or moves. So, thinking about it on a local level, the number of baptisms in a congregation has nothing to do with the increase or decrease in the number of publishers.