VATICAN CITY -- Cardinal Crescenzio Sepe, the retired archbishop of Naples, celebrated his 80th birthday June 2 and, consequently, became ineligible to enter a conclave to elect a new pope.

The cardinal's aging out left the College of Cardinals with 121 clerics under the age of 80 and eligible to vote.

Of those 121 cardinals, 81 -- 66.9% -- were inducted into the college by Pope Francis.

According to modifications to the norms governing the election of the bishop of Rome promulgated by Pope Benedict XVI in 2013 and still in force, "a majority vote of two-thirds of the cardinal electors present is always necessary for the valid election of a Roman Pontiff."

With Cardinal Sepe's birthday, just over two-thirds of the currently eligible voters were made cardinals by Pope Francis.

Another seven cardinals -- including three given their red hats by Pope Francis -- will celebrate their 80th birthdays before the end of the year. They include Cardinal Juan Cipriani Thorne, former archbishop of Lima, Peru, who was made a cardinal by St. John Paul II; and Cardinals Giuseppe Versaldi, Angelo Comastri and Leonardo Sandri, all retired Vatican officials who were made cardinals by Pope Benedict.

The almost-80-year-olds inducted into the College of Cardinals by Pope Francis are: Cardinals Patrick D'Rozario, retired archbishop of Dhaka, Bangladesh; Andre Yeom Soo-jung, retired archbishop of Seoul; and Jean Zerbo, archbishop of Bamako, Mali.

According to rules set by St. Paul VI and never abrogated, but frequently set aside for months at a time over the past three decades, the College of Cardinals can have a maximum of 120 members eligible to vote in a conclave.