The Global Power Index is created by the Pardee Center for International Futures and is used by the National Intelligence Council in the Global Trends report which is released every 5 years, as well as their reports to the US government.
The most recent IFs index was updated in 2016 and contains projections for every year up to 2100. The GPI weighs countries by Economy (35%), Military (25%), Political Influence (20%), Population (10%) and Technology (10%) using various sub-metrics within each category to produce an overall rating.
In 2020, the Top 20 projected nations were as follows:
- United States: 22.4% of global power
- China: 15.1%
- Japan: 5.2%
- Germany: 4.8%
- France: 4.7%
- United Kingdom: 4.1%
- Russia: 4.0%
- India: 3.7%
- Brazil: 2.1%
- Italy: 2.0%
- Canada: 1.9%
- Australia: 1.6%
- South Korea: 1.5%
- Saudi Arabia: 1.5%
- Spain: 1.5%
- Netherlands: 1.3%
- Mexico: 1.0%
- Indonesia: 1.0%
- Turkey: 0.9%
- Israel: 0.8%
Generally, the relative positioning looks fairly accurate in my opinion. If anybody has questions about the methodology or comments to add ask below. I also have a spreadsheet of past and projected ratings if there is interest. Some interesting side-notes about the index:
- The USA surpassed Britain as the world’s top power in 1897 in terms of material capabilities.
- Prior to WW2, Germany and the US were the primary powers (~21% each), with the Soviet Union and British Empire close behind (~15% each)
- The UK was at its zenith in world power during the 1820s.
- US Global Power peaked in 1951 at 50%.
- China will supposedly overtake the US in 2030.
- There will be three ‘Great Powers’ during the 21st century consisting of China, the US and India (as well as the EU if fully integrated)
Here is the methodology for the ranking (and previous versions): pardee.du.edu/sites/default/files/Power%20Codebook%2020180702.pdf
Here is a spreadsheet with historical ratings from 1816-2100: