Currency Exchange Rates have been hovering around equal work time ever since the International Monetary Fund began collecting the data necessary to see it. Figure 6.1 shows that relationship for 93 countries in 2008.
The center line in Figure 6.1 represents equal work time.
Countries above that line are paying more than equal work time for the currencies of countries below the line.
Countries below that line are paying less than equal work time for the currencies of countries above the line.
For trade to be fair, all countries should have exchange rates that put them on the center line.