Pope Francis passes past a portrait of himself as he arrives to meet youths in Santo Tomas University in Manila, Philippines, Sunday, January 18, 2015. Francis is in the Philippines on Sunday, the final full day of a weeklong trip that also took him to Sri Lanka. (Photo by Alessandra Tarantino/AP Photo)

Alfred Yetta (L) and Kay Manning pose for a photo in front of a cardboard cut-out of Pope Francis, during an event organised by Christa Scalies, the co-creator of the Pop-Up Pope, in Fado Irish Pub & Restaurant in Philadelphia, Pennsylvania, September 16, 2015. (Photo by Mark Makela/Reuters)

Dancers from the Philadelphia Ballet perform for Pope Francis (R) as he attends the Festival of Families rally in Philadelphia, Pennsylvania September 26, 2015. (Photo by Brian Snyder/Reuters)

Activists protest against the upcoming visit of Pope Benedict XVI on the eve of his arrival on September 21,2011 in Berlin, Germany. A variety of groups, including the poltically left-wing as well as gay and lesbian rights advocates, partook in the demonstration. The Pope is scheduled to visit Germany from September 22–25. (Photo by Sean Gallup/Getty Images)

A faithful prays during the Divine Liturgy by Pope Francis at the apostolic Cathedral in Etchmiadzin, Armenia, June 26, 2016. (Photo by David Mdzinarishvili/Reuters)

Boys walk home for lunch from school in the village of Kogelo, west of Kenya's capital Nairobi, July 16, 2015. U.S. President Barack Obama visits Kenya and Ethiopia later this month. His ancestral home of Kogelo is home to Sarah Hussein Obama, his step-grandmother. The Kenyan village, burial place of Obama's father, features an open-pit goldmine, a pork butcher's, a school named after their most famous son and outdoor market stalls. Villagers get around by motorbike taxi or on foot while a donkey-cart transports water. Children, some of them named Obama in honour of the President, walk to and from school together. (Photo by Thomas Mukoya/Reuters)

President Barack Obama speaks to the press in the Briefing Room of the White House April 27, 2011 in Washington, DC. US President Barack Obama released a long form version of his birth certificate after extended criticism by those who do not believe he was born in the United States. (Photo by Brendan Smialowski/Getty Images)

Nuns from the United States dance as they wait for the Holy Mass with Pope Francis (not seen) at the Campus Misericordiae in Brzegi, Poland, 31 July 2016. Today Pope Francis will celebrate the holy mass ending the World Youth Day 2016 in Poland. (Photo by Marcin Obara/EPA)