BEIJING — China’s migrants numbered 244.5 million in 2017, 820,000 less than in 2016, according to an official report.

China’s migrant population, people who leave their hometown to seek employment or education elsewhere, continued to grow for decades but began a slow decline starting in 2015, said an annual report on migrants released by the National Health Commission.

The number of elderly migrants kept growing but the number of child migrants dropped in the past few years, according to the report.

The moving population has generated demographic dividend during the past decades, as a large amount of surplus of labor in rural China moved into the cities to create wealth for both their own families and society, said the report.

The report showed that more of the migrant population has shifted from the primary industry to the service sector since 1978.

In 1978, 70.5 percent of the migrant population worked in the primary industry while only 12.2 percent in the service industry. In 2016, 27.7 percent worked in the primary industry and 43.5 percent in the service sector.

As the labor and resource-intensive industries are moving from eastern China to central and western China in recent years, the migrant population has followed the same move, said the report.