4-5% unemployment is actually full employment from a macroeconomics perspective. There always be forms of static, cyclical, and I forget the name of the third, but I can still describe ethem. Static unemployment comes from people having skills that don't match the demands of the economy, they are unemployed while they learn new skills. Cyclical comes from the growth and recession curve of the business cycle (google business cycle if you need further explanation of that). The final comes from people just having difficulty linking up with people wanting to hire them, such as new college graduates not knowing how to meet up and find the companies wanting to find them. These three types of employment will always exist in a capitalist system, and when minimized will result in a 4-5% unemployment rate according to macro-economists (I can provide sources when I get back to my dorm tommorow if need be).