Research on the Measurement of Logistics Capability of Core Cities along “the Belt and Road” in China

Table 1

Urban energy level index system and data source.

Primary index	Secondary index	Data source
Urban economic strength	GDP	Wind database
	The total volume of retail sales	National Bureau of Statistics (NBS)
	The proportion of gross product of secondary industry in GDP	Wind database
Urban investment and construction capacity	Investment in fixed assets of the whole society	Wind database
Urban external circulation capacity	Urban freight volume	National Bureau of Statistics (NBS)
	Urban passenger traffic	National Bureau of Statistics (NBS)