ODA, with aid worth less than 10% of collected taxes in Africa as a whole. However, in a quarter of African countries Overseas Development Assistance does exceed tax collection, with these more likely to be non-resource-rich countries. This suggests countries making the most progress replacing aid with tax revenue tend to be those benefiting disproportionately from rising prices of energy and commodities. The author found tax revenue as a percentage of GDP varying greatly around a global average of 19%. This data also indicates countries with higher GDP tend to have higher tax to GDP ratios, demonstrating that higher income is associated with more than proportionately higher tax revenue. On average, high-income countries have tax revenue as a percentage of GDP of around 22%, compared to 18% in middle-income countries and 14% in low-income countries. In high-income countries, the highest tax-to-GDP ratio is in Denmark at 47% and the lowest is in Kuwait at 0.8%, reflecting low taxes from strong oil revenues. The long-term average performance of tax revenue as a share of GDP in low-income countries has been largely stagnant, although most have shown some improvement in more recent years. On average, resource-rich countries have made the most progress, rising from 10% in the mid-1990s to around 17% in 2008. Non-resource-rich countries made some progress, with average tax revenues increasing from 10% to 15% over the same period. Many low-income countries have a tax-to-GDP ratio of less than 15% which could be due to low tax potentials, such as a limited taxable economic activity, or low tax effort due to policy choice, non-compliance, or administrative constraints. Some low-income countries have relatively high tax-to-GDP ratios due to resource tax revenues (e.g. Angola) or relatively efficient tax administration (e.g. Kenya, Brazil) whereas some middle-income countries have lower tax-to-GDP ratios (e.g. Malaysia) which reflect a more tax-friendly policy choice. While overall tax revenues have remained broadly constant, the global trend shows trade taxes have been declining as a proportion of total revenues(IMF, 2011), with the share of revenue shifting away from border trade taxes towards domestically levied sales taxes on goods and services. Low-income countries tend to have a higher dependence on trade taxes, and a smaller proportion of income and consumption taxes when compared to high-income countries. One indicator of the taxpaying experience was captured in the 'Doing Business' survey, which compares the total tax rate, time spent complying with tax