@Cat_LeFey Also, the number is skewed, e.g., there may be 1.422 billion catholics according to the Vatican, but how many of those are really more secular now? Many probably.
I stopped attending church around 1997, but didn't request a note of departure to be placed in the baptismal register until 20 years later. Many people never request that or know about it. Even then, theologically baptism is permanent and the entry won’t be deleted, just appended to that you’re no longer an active member.