Fig. 6

City-level energy efficiency in China obtained from energy consumption of per unit GDP. (a) The energy efficiency in 1997, (b) the energy efficiency in 2003, (c) the energy efficiency in 2010, (d) the energy efficiency in 2017.
City-level energy efficiency in China obtained from energy consumption of per unit GDP. (a) The energy efficiency in 1997, (b) the energy efficiency in 2003, (c) the energy efficiency in 2010, (d) the energy efficiency in 2017.