Taxation constitutes one of the main elements of government management—which includes empirical observations and thought regarding the role of government in economic development. Taxes themselves comprise – rightly so – the main source of a country's income. Based on this income, the government can regulate economic conditions and growth, rates of unemployment and inflation, leading not only toward economic ends (such as increasing per capita income, economic growth, reducing unemployment and stabilizing the economy) but also, social improvement ends, such as equity, education and health. Nicholas Kaldor – a leading British economist – argued that in order to progress, a country must be able to collect taxes amounting to 25 to 35% of its gross domestic product (GDP). Although calling for a lower target, the UN Millennium Project in 2005 stressed the need for a 4% increase from the current average tax-income-to-GDP percentage, namely 18%. In principle, the state, as a producer involved in the creation of value together with the whole society, earns income in four forms. The first of these is Direct Taxes, that is, part of the income that is generated through the production of commodities, which constitutes part of the surplus value and wages produced in a given period. The second is Public Loans, for example, state issued bonds that people purchase using the surplus value they have accumulated, in the expectation of gaining additional surplus value from their investments. The third form is Indirect Taxes, such as excise tax (on imported commodities as well as commodities that circulate in country, such as cigarettes), sales tax and valueadded tax.