All data are from the CIA World Factbook (website:
https://www.cia.gov/library/publications/the-world-factbook/).
A new parameter may be used for estimating a country's GDP, using its GDP (in US dollar based on nominal rate) divided by annual electricity production (AEP in kwh). This parameter is referred to as GDP/AEP, i.e. unit kwh dollar values. A few countries are listed below simply for comparison.
GDP/AEP
USA 4.4
China 1.8
Brazil 3.1
Argentina 4.4
Malaysia 2.3
This is intriguing. For example, one kwh electricity in USA generates $4.4 GDP. However, the same unit electricity in China can only produce $1.8 GDP. What does this suggest? The physical law, however, cannot be wrong. Think about that.
It is debatable though. The efficiency of using electricity is different in different countries, depending on many facts, e.g. technological level, labor skills. The USA may have the same level as Argentina in terms of using electricity efficiency. Brazil and Malaysia have higher efficiency of using electricity than China. Obviously, something appears not right by such a comparison. The USA is much more developed than Argentina, while Brazil and Malaysia are clearly less developed compared to China. This suggests that something must be wrong when estimating a country's GDP. If so, the Argentina and Brazil GDP are overestimated, whereas China GDP is much undercounted.
If using the average GDP/AEP value of the above five countries, 3.2, as an arbitrary parameter to measure each of these countries GDP, then a correction factor can be obtained. In other words, USA GDP would be reduced by a factor of 3.2/44 (0.76), i.e. its 2017 GDP would be 15 trillions dollars; China GDP would be raised by a factor of 1.78, and the China 2017 GDP would be increased to 21 trillions dollars. Similar calculations may be done for Brazil, Argentina, and Malaysia.
The conclusion is simple that China has overtaken the USA as the largest economy in terms of exchange rate since last year (see the CIA website above).