BEIJING — China continued to lead the world in courier delivery volume in 2016, a report showed Tuesday.

China made up over 40 percent of global express delivery volume last year, contributing about 60 percent to the sector's growth, according to a report released by the State Post Bureau (SPB).

The total number of packages delivered increased by 51.4 percent year-on-year in 2016 to more than 31 billion.

Last year, couriers delivered over 4 trillion yuan worth of retail sale products that had been bought online, accounting for 12.5 percent of total retail sales, the report showed.

The delivery network expanded from 4.8 depots per 100,000 people and 6.7 depots per 1,000 square kilometers in 2010 to 15 and 19.1 depots, respectively, in 2016, according to the report.

Meanwhile, service quality also improved, with fewer complaints.