Already the longest-lived of the 45 men to serve as U.S. president, Jimmy Carter is about to reach the century mark. The 39th president, who remains under home hospice care, will turn 100 on Tuesday, Oct. 1, celebrating in the same south Georgia town where he was born in 1924. Video above: President Jimmy Carter in 1977Here are some notable markers for Carter, the nation and the world over his long life. Carter has seen the U.S. population nearly triple. The U.S. has about 330 million residents; there were about 114 million in 1924 and 220 million when Carter was inaugurated in 1977. The global population has more than quadrupled, from 1.9 billion to more than 8.1 billion. It already had more than doubled to 4.36 billion by the time he became president.That boom has not reached Plains, where Carter has lived more than 80 of his 100 years. His …