According to one report, over half the jobs done by humans today are vulnerable to being replaced by robots within just a few decades, all of which would represent over $15 trillion worth of wages worldwide that will not be taxed. The solution, in Gates' mind, is simple: tax the robots. Some of the lost revenue may, in fact, be made up automatically in the form of higher tax returns from the increased profits of manufacturers saving on labor costs. However, given that many countries do not use a proportional or flat tax system, lumping the income together for a single entity (the proprietor or the company) instead of dividing it between different individuals will eventually lead to a significant loss in revenue. To make up for this, Gates believes we may use a combination of higher taxes on companies as a result of their higher profits and the possibility of taxing the companies that make the robots designed to replace human workers.