 Nearly all developed countries provide all their residents with access to a broad set of public health and individual medical interventions. In these countries access to care is assured despite income and wealth inequalities through universal coverage health systems. The method of financing these universal access systems, as well as their organizational structure, varies considerably. Some systems are funded through general tax revenues as in Canada; others through payroll taxes, as in several European countries; and others through a mix of public and private insurance schemes, as in Germany. Thus some systems are more progressively financed than others, since general tax revenues are more progressive than social security or payroll taxes, and these in turn are more progressive than insurance premiums. (In a progressive tax scheme, the rate increases as the amount that is taxable increases.) Some systems have public ownership of hospitals, with physicians and nurses as salaried employees of the public system, as in the United Kingdom or Norway. Others contain a mix of public and private institutions, though with extensive public regulation of the benefit packages available to people, as in Germany. Some systems allow no insurance schemes except the universal coverage scheme, as in Canada and until recently Norway; others allow supplementary insurance, as in the United Kingdom.