BEIJING — As a main aspect of the digital economy, internet economy has become a key engine for China's new economic driver, official data showed.

The internet economy index, one of the five sub-indexes of the new economic driver index, contributed 80.8 percent to the growth of the combined index in 2018.

China has seen a stable and fast growth of the new economic index since 2014, and saw a growth rate of 28.7 percent last year.

As a main component of the internet economy, the number of mobile internet users in China reached 1.4 billion in 2018, up 9.9 percent year-on-year.

The country also recorded 31.6 trillion yuan (about $4.6 trillion) in e-commerce transactions in 2018, up 8.5 percent year-on-year.

"Composed by new industry, new formats and new models, China's new economic driver is expanding, unleashing the vitality of the economy and supporting its high-quality development," said Lyu Haiqi, an official with the National Bureau of Statistics.