Major South Korean companies are seeing an increase in the percentage of employees aged 50 or older, while that of employees in their 20s is declining, a recent report by corporate analysis firm Leaders Index showed Tuesday.

The firm analyzed 2021-23 data of 141 companies among the top 500 in the country in terms of sales, compiling the report on 123 companies that also revealed the ages of their employees. The total number of employees at those companies went from 1.38 million in 2021 to 1.42 million in 2023, marking an increase across all three age groups of those in their 20s, those aged 30 to 49 and those aged 50 and over.

However, employees in their 20s declined from 23.4 percent of all workers in 2021 to 21.6 percent in 2023. Employees aged at least 50 increased from 20.6 percent to 22 percent in the same period.

The shift in demographics was more pronounced in the information technology and electronics industry, which marked a drop of 5.3 percentage points in the youngest age group -- 34.2 percent to 28.9 percent. The rechargeable battery industry marked the steepest drop in the percentage of 20-something employees, going from 40 percent in 2021 to 34.2 percent in 2023.

The food and beverages industry, on the other hand, marked the steepest increase in terms of 50 and older employees, going from 24.6 percent to 28.8 percent.

By company, Samsung Electro-Mechanics marked the steepest drop in the percentage of young employees. About 48.4 percent of its employees were in their 20s in 2021, which dropped to 40.1 percent two years later.

Samsung Electronics marked the steepest drop in total number of younger employees, going from 89,897 to 72,525 in the same period.

Of all the companies surveyed, 22 companies had over three times more 50-something employees than 20-something employees. Kia in particular had 7.8 times more employees in the oldest group compared to the youngest group.

An aging population has been a chronic issue in South Korea, coupled with the consistently falling total fertility rate of the country.

In April, South Korea marked an average age of 45 for all its citizens. It was the first time the country surpassed the mark of 45, and was 5.3 years older than the 39.7 recorded in 2014.