Figure_6b is plotted by Qin Liu (qinliu.christoph@gmail.com).

Comments on .csv files:
- Global_pop.csv contains population data for all countries, which is same with Population_(Millions).xls in /Raw Data but has deleted data for regions and replaced all 'NA' by 0s.
- TotalCO2.csv contains CO_2 emission data for all countries, which is same with Total_Carbon_Dioxide_Emission_from_Energy_Consumption_(Metric_Tons).xls in /Raw Data but has deleted data for regions and replaced all 'NA' by 0s.
- cepercap.csv contains CO_2 per capita data for all countries, which is calculated using Global_pop and TotalCO2. Emission Per Capita for A=(Emission of A)/(Population of A).