Figure 4. Energy per capita for the different groups of countries as a function of time. The difference in the growth tendency for the industrial and developing countries is reflected via the slope values (tg ф) of these lines. Calculated from data given in ref.

From

Global Energy Consumption Rates: Where is the Limit?

Oleg P. Dimitriev

Sustainable Energy. 2013, 1(1), 1-6 doi:10.12691/rse-1-1-1