A topic frequently in the news is the health (or lack thereof) of the US Social Security system. As in many nations, the US Social Security system is pay as you go: revenue received today from taxes paid by workers and their employers is used to pay benefits to those over the age of sixty-five. For the purpose of this question, assume that people start working at age twenty and begin receiving social security benefits at age sixty-five. Map the stock and flow structure of the US population as it relates to the social security system. Also map the stock and flow structure of money as it goes through the system. You should have two separate stock flow chains in this answer, one for people, one for money. Make sure they are appropriately linked with information arrows. Not every dollar received today is paid out today. In fact, at various points in time, the system has had a substantial surplus. Make sure this is captured in your diagram. Every model is built towards a specific purpose. If the goal of this effort is to understand the basic dynamics of social security, how complicated does your stock and flow structure representing the US population need to be? Do not make your diagram any more complicated than necessary.