If the size of the entire dataset increases, but your share of that dataset does not increase at the same rate, youj are shrinking. That's why comparative numbers are always expressed as a % of the whole or for populations, x/100,000.Christianity isn't dwindling; it's increasing. The RCC Church is adding numbers. Even in America. I wish you guys could take a basic math course and understand that a decreased percentage of an increasing population does not mean raw numbers have decreased.