Between 2006 and 2019, around two thirds of climbers were successful in their attempt to reach the top. In the 15 years before that, only about one-third went all the way to the top.
The study was a project of researchers at the University of Washington and the University of California, Davis. They found that the risk of dying on the mountain was 0.5 percent for women and 1.1 percent for men in recent years. That is down from 1.9 percent and 1.7 percent in the period from 1990 to 2005, the researchers said.
The number of attempts to reach the top of Everest has risen sharply over the years, leading to a 300 percent increase in overcrowding. In 2019, 955 climbers tried to reach the mountaintop. Only 222 people did so in 2000.
The study noted that on a single day in May of last year, 396 climbers had gathered at the narrow path just below the top. The area, known as the "death zone," is so narrow that only a small number of climbers can pass through, one directly behind another.
Nine climbers died on Everest in May 2019. It was the deadliest Everest climbing season since 2015 when an earthquake killed at least 18 people on the mountain.
A picture of climbers waiting their turn to go up and down through the death zone became famous as it was shared online. Yet researchers say the crowds were not the main reason for the deaths last year.
"Surprisingly crowding has no evident effect on success or death" of Everest climbers, the study said.
However, overcrowding does make the climb more dangerous.
"If crowding slows climbers (as is expected), this increases their exposure to the elements, which should increase risk of an accident or illness," said Raymond B. Huey, lead writer of the report.
An unexpected storm, earthquake, or landslide could be disastrous, he told Reuters by email.
Climbers have expressed concern that Nepal was giving anyone willing to pay the government $11,000 permission to climb Everest. Nepal plans to change its policy to require climbers to use guides, and meet physical fitness and experience qualifications, said tourism department official Mira Acharya.
Nepal temporarily closed its mountains to climbers because of the coronavirus health crisis. Now they are open again. However, Acharya noted that flights into and within Nepal have not restarted.
More than 6,000 people have climbed Mount Everest since 1953, when New Zealander Edmund Hillary and Sherpa Tenzing Norgay became the first climbers known to reach the top. At least 311 climbers have died trying.
I'm Caty Weaver.