BEIJING, July 9 (Xinhua) -- China-Europe freight trains have made over 9,000 trips by the end of June, the China Railway Corporation (CRC) said Monday.

Since the services began in 2011, the trains have delivered 800,000 twenty-foot equivalent units (TEUs) of goods, connecting 48 Chinese cities with 42 European cities, according to CRC.

For more than 7 years, the services have been improving connectivity between Chinese and European cities, boosting economic and trade ties.

Zhang Wei, an engineer with China Railway Container Transport Corporation, said he has witnessed the development of the freight trains, with the number of trains departing from southwest China's Chongqing Municipality increasing steadily over the years.

"For me, the China-Europe freight train is like a kid. As it grows up gradually, I feel so proud," Zhang said.

In 2017, more than 3,000 trips were made via the China-Europe freight trains between cities on the two continents. The number of trips is expected to reach 4,000 in 2018, said CRC.