The primary hormone produced by the male testes is testosterone, a steroid hormone important in the development of the male reproductive system, the maturation of sperm cells, and the development of male secondary sex characteristics such as a deepened voice, body hair, and increased muscle mass.
Foreign investments in the US average $2.4 trillion, while American investments in other countries total $3.3 trillion. Consumer spending comprised 71% of the US economy in 2013, and the United States has the largest consumer market in the world. As a result, the US possesses not only the largest economy, but also one of the most stable in the world. Economic History. The United States has had the world's largest national economyânot including the benefit of colonial empiresâsince the 1890s.
For the most part, the United States has a market economy in which individual producers and consumers determine the kinds of goods and services produced and the prices of those products. The most basic economic institution in market economies is the system of markets in which goods and services are bought and sold. That is where consumers buy most of the food, clothing, and shelter they use, and any number of things that they simply want to have or that they enjoy doing.