An Arkansas woman who just celebrated her 116th birthday isn’t as unusual as some might think. Gertrude Weaver — officially the oldest living American and second-oldest person in the world — belongs to a fast-growing segment of the U.S. population: people who are 100 years old or older. There are about 53,000 centenarians in the U.S. today. VOA’s Julie Taboh shares their secrets to longevity.