Figure 1 shows the evolution curve of the average in-degree of the FEIT each year. The average in-degree of
FEIT grew from 7.44 in 1996 to 12.9 in 2012, while reflecting more countries join the fossil energy international
trade with the development of economic globalization and the capacity is increasing; on the other hand, it
showed the energy trade links between countries are getting closer and interdependence of energy is deepening