the most commonly used way to measure the size of the underground economy, is is based off of the assumption that most underground activity uses currency. using this, guesstimates can be made... the problem is, that it leaves no room to make changes in how people use currency and coins or official reported purchases... but, it is still widely used. the us has the smallest percentage of underground economics (in 2015). Romania had the largest percentage. (in 2015). how do you suppose that different levels of government business regulations and varying levels of enforcement of those regulations might affect the size of the underground economy?