Social economics recognises strongly that money is a social relation. Money supply grows at a conventional interest rate, which is an interest rate which investors find reasonable given expected inflation and perceived risks. The neoclassical theory of money and inflation is called monetarism. The money in a modern economy is not based on gold or bank reserves or any guarantee by the state. Central Banks still keep some gold reserves, because this helps them to sell reserves in times of need and to buy reserves in times of prosperity: gold reserves allow Central Banks to buy in international currency markets foreign currency or their own currency. The regulation imposed after the 1929 crisis has been gradually undone since the 1980s under the influence of the widespread belief among Central Bankers, academic economists, and politicians in the efficient market hypothesis (EMH).