Statistics Saturday: Papal Regnal Numbers Over Time, 1900 – Present

Line chart of Papal regnal numbers for each year from 1901 to through 2021; eg, Leo XIII (13), Pius X (10), Benedict XV (15), up to today's Francis (I). Also across this is a red line showing the number has been, on average, decreasing with time.
The red line is the best-fit linear interpolation of these numbers over time. The projection is that if trends of the past 120 years continue then sometime in the year 2070 we can expect a Pope with regnal number of 0.

Reference: Pluto and Charon: Ice Worlds on the Ragged Edge of the Solar System, Alan Stern and Jacqueline Mitton.