American adults smoked for so many years before the 1964 landmark report that links smoking and disease, but has gone down to about 18 percent according to a new study.

The new study published online in the Journal of the American Medical Association (JAMA) said that anti-smoking measures have saved roughly 8 million adults in the U.S. thanks to the 1964 report. The study also said that the figure could have been higher if the 1964 report was not published.

This week's issue of the journal commemorates the 50th anniversary of the surgeon general report that was credited for raising alarms about the dangers and hazards of smoking, according to MSN News.

Researchers from one of the studies used national health surveys and death rates to calculate how many Americans could have died if the report didn't come out. Their calculations found that 8 million Americans could have died over the course of many years and thanks to the report it didn't happen.

The report also included how tobacco controls substantially contributed to increases in life expectancy of Americans. In one example, it showed that 40-year-old Americans have more than five years of longer life since the publication of the 1964 report. The report said that tobacco control accounted for about 30 percent of life expectancy gains.

The results of the new study are just estimates and should not be construed as hard evidence, but Theodore Holford, lead author of the study, said that their calculations "are pretty striking."

However, smoking among American adults remains a problem and is still linked to heart disease, cancer, stroke, and various lung ailments. These diseases are the top leading causes of death in the U.S.

For instance, the U.S. Centers for Disease Control (CDC) estimated 443,000 Americans still die annually from smoking-related conditions.

"Tobacco is, quite simply, in a league of its own in terms of the sheer numbers and varieties of ways it kills and maims people," Dr. Thomas Frieden, the CDC's director, wrote in a JAMA commentary.

"Images of smoking in movies, television and on the Internet remain common; and cigarettes continue to be far too affordable in nearly all parts of the country," Frieden wrote.