Based on the principle of solidarity and compulsory membership, the calculation of fees differs from private health insurance in that it does not depend on personal health or health criteria like age or sex, but is connected to one's personal income by a fixed percentage. The aim is to cover the risk of high cost from illness that an individual can not bear alone.
The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress". Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity". Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.
Currently 85% of the population is covered by a basic health insurance plan provided by statute, which provides a standard level of coverage. The remainder opt for private health insurance, which frequently offers additional benefits. According to the World Health Organization, Germany's health care system was 77% government-funded and 23% privately funded as of 2004.