BOCA RATON, Fla. » Not too long ago, Lonny Fried’s achievement would have dropped jaws. TV and newspaper reporters would have showed up at her door. She would have been fussed over and given a big party.

But turning 100 isn’t such a big deal anymore.

America’s population of centenarians — already the largest in the world — has roughly doubled in the past 20 years to around 72,000 and is projected to at least double again by 2020, perhaps even increase seven-fold, according to the Census Bureau.

Fried turns 100 on Friday. Her retirement community, Edgewater Pointe Estates in Boca Raton, observed her birthday two weeks ahead of time with other residents born in April.

“In the ‘80s, we’d make a big deal about it by calling Willard Scott on TV to make that huge announcement,” Diana Ferguson, who has worked at Edgewater for 25 years, said of the “Today” show weatherman known for his on-air birthday wishes to viewers who hit the century mark. “But today we have so many residents turning 100-plus that it’s not as big a deal.”

Fried doesn’t mind at all. Simply making it to 100, she said, is enough.

“I don’t want any celebration or nothing,” she said.

Born in Germany, she lost her first husband in the Holocaust and was herself held at the Westerbork concentration camp before coming to the U.S. She takes no medication, moves around steadily with a walker and said she has been fulfilled by a life in which she found a second love, raised a family and worked as a nurse.

“I still don’t believe it,” she said.

The Census Bureau estimates there were 71,991 centenarians as of Dec. 1, up from 37,306 two decades earlier. While predicting longevity and population growth is difficult, the census’ low-end estimate for 2050 is 265,000 centenarians; its highest projection puts the number at 4.2 million.

“They have been the fastest-growing segment of our population in terms of age,” said Thomas Perls, director of the New England Centenarian Study at Boston University.

The rising number of centenarians is not just a byproduct of the nation’s growing population — they make up a bigger chunk of it. In 1990, about 15 in every 100,000 Americans had reached 100; in 2010, it was more than 23 per 100,000, according to census figures.

Perls said the rise in 100-year-olds is attributed largely to better medical care and the dramatic drop in childhood-mortality rates since the early 1900s. Centenarians also have good genes on their side, he said, and have made common-sense health decisions, such as not smoking and keeping their weight down.

“It’s very clearly a combination of genes and environment,” Perls said.

The Social Security Administration says just under 1 percent of people born in 1910 survived to their 100th birthday. Some have speculated that as many as half of girls born today could live to 100.

Those who work with people 100 and above say the oldest Americans are living much healthier lives. A good number still live independently and remain active, their minds still sharp and their bodies basically sound. They have generally managed to confine serious sickness and disability to the final years of their lives.

When Lynn Peters Adler, a former lawyer who founded and runs the National Centenarian Awareness Project, began to recognize the oldest members of the community, she didn’t even know the word “centenarian.” Now, some weeks she talks to a dozen people who are 100 and older. And in her 25 years of contact with centenarians, she has culled some similarities among them:

>> A positive but realistic attitude.

>> A love of life and sense of humor.

>> Spirituality.

>> Courage.

>> And a remarkable ability to accept the losses that come with age but not be stopped by them.

“Centenarians are not quitters,” she said.

Peters Adler cautioned against growing too accustomed to centenarians, saying they still deserve to be recognized. After all, census estimates indicate they represent only about one out of every 4,300 Americans.

“It’s a great distinction,” Peters Adler said. “I think we’re sort of shortchanging everything if we become blase about it or say it’s not enough to be 100 anymore, you have to be 110.”

For their part, some centenarians aren’t as wowed by the magic number.

Leo Lautmann, who lives at the Hebrew Home at Riverdale in New York City, reached 100 in December. He paused for a moment when asked how long he’d like to live.

“One hundred and twenty,” he said in Yiddish, before reconsidering. “Maybe 110 would be enough.”