There are more than 900 million Protestants worldwide,[ad] among approximately 2.4 billion Christians.[ae] In 2010, a total of more than 800 million included 300 million in Sub-Saharan Africa, 260 million in the Americas, 140 million in Asia-Pacific region, 100 million in Europe and 2 million in Middle East-North Africa. Protestants account for nearly forty percent of Christians worldwide and more than one tenth of the total human population. Various estimates put the percentage of Protestants in relation to the total number of world's Christians at 33%, 36%, 36.7%, and 40%, while in relation to the world's population at 11.6% and 13%.
Hafizullah Amin (Pashto/Dari: حفيظ الله امين‎; born 1 August 1929 – 27 December 1979) was an Afghan communist politician during the Cold War. Amin was born in Paghman and educated at Kabul University, after which he started his career as a teacher. After a few years in that occupation, he went to the United States to study. He would visit the United States a second time before moving permanently to Afghanistan, and starting his career in radical politics. He ran as a candidate in the 1965 parliamentary election but failed to secure a seat. Amin was the only Khalqist elected to parliament in the 1969 parliamentary election, thus increasing his standing within the party. He was one of the leading organizers of the Saur Revolution which overthrew the government of Mohammad Daoud Khan. In 1979 he named himself president, prime minister, and chairman of the Khalq wing. He has been described as "ruthless" and a "radical Marxist".Amin's short-lived presidency was marked by controversies from beginning to end. He came to power by disposing of his predecessor Nur Muhammad Taraki and later ordering his death. Amin made attempts to win support from those who revolted against the communist regime which had begun under Taraki, but his government was unable to solve this problem. Many Afghans held Amin responsible for the regime's harshest measures, such as ordering thousands of executions. Thousands of people disappeared without trace during his time in office. The Soviet Union, which was dissatisfied with Amin, intervened in Afghanistan while invoking the Twenty-Year Treaty of Friendship between Afghanistan and the Soviet Union. Amin was assassinated by the Soviets on December 27, 1979 as part of Operation Storm-333, having ruled for slightly longer than three months.
The majority of U.S. adults self - identify as Christians, while close to a quarter claim no religious affiliation. According to a 2014 study by the Pew Research Center, 70.6% of the adult population identified themselves as Christians, with 46.5% professing attendance at a variety of churches that could be considered Protestant, and 20.8% professing Catholic beliefs. The same study says that other religions (including Judaism, Buddhism, Hinduism, and Islam) collectively make up about 6% of the population. According to a 2012 survey by the Pew forum, 36% of U.S. adults state that they attend services nearly every week or more. According to a 2016 Gallup poll, Mississippi (with 63% of its adult population described as very religious, saying that religion is important to them and attending religious services almost every week) is the most religious state in the country, while New Hampshire (with only 20% of its adult population described as very religious) is the least religious state.

Question: What is the total population of people who belong to the largest religious group in the country Amin visited for the second time?
Answer: approximately 2.4 billion