Non-tax revenues fluctuate much more from one year to another than taxes — three times as much in the European Union,[7] and slightly less than that for the globe as a whole.
[8] Many countries in Africa can report changes in non-tax revenue of over 35 percent from one year to another due to variations in the price of their natural resources.
Moreover, some years are marked by exceptional events: for example, in France in 2012, the sale of "4G" radio frequencies resulted in the collection of nearly €1.3 billion in non-tax revenues.
[10] The presence of large non-tax revenues — invariably from non-renewable natural resources, foreign aid, or strategic rents like those associated with the Suez Canal — has been shown to make democratisation much less possible.
[2] For instance, it has been calculated that foreign aid has reduced tax revenue in sub-Saharan Africa by ten percent.