South Korea's population posted a decrease for the first time last year.

The Ministry of the Interior and Safety said on Sunday that as of the end of 2020, just over 51-point-82 million people were registered as the country's residents, down over 20-thousand from the previous year.

The population had posted a slight and steady increase over the past decade, but the pace of growth slowed since 2016 and finally declined for the first time last year.

However, the number of households continued to increase in recent years, adding more than 611-thousand on-year to 23 million last year.

The average number of household members fell to a record low of two-point-24 last year, with the number of one-member households surpassing nine million for the first time.

Single households accounted for nearly 40 percent of the country's total households last year.