For the years 1971 to 1989 the data source is
World Bank.
For the years 1990 to 1991 the data source is
IEA.
For the years 1992 to 1999 the data source is
EIA.
For the years 2000 to 2016 the data source is
Ember.
For the years 2017 to 2018 the data source is
IEA.
For the years 2019 to 2022 the data source is
Ember.