Although two of the five popes before Pope Francis have been named saints, merely serving as pontiff is not a shoo-in to canonization. At least not anymore.
In the early years of the Roman Catholic Church, most popes, starting with St. Peter, who is considered the first to hold the seat, were named saints after they died. Of the first 50 popes, 48 got the honor. Over time, it became much rarer.
To date, 80 of the 266 popes to serve over nearly 2,000 years have been canonized. Another 11 are on a waiting list of sorts, having been beatified, the penultimate step to sainthood.