that is "a 10 percent decrease in securities industry employment would depress employment in the retail, services, and restaurant sectors by more than 1 percent; in the business services sector by about 4 percent; and in total private jobs by about 1 percent." It is also possible to estimate the impact of a reduction in stock market volume caused by taxing stock transactions on the rise in the overall unemployment rate. For every 10 percent decline in stock market volume, elasticities estimated by Schwabish implied that a stock transaction ("transfer") tax could cost New York City between 30,000 and 42,000 private-sector jobs, and if the stock market volume reductions reached levels observed by Umlauf (1993) in Sweden after a stock FTT was introduced there ("By 1990, more than 50% of all Swedish trading had moved to London") then according to Schwabish (2005), following an introduction of a FTT tax, there would be 150,000-210,000 private-sector jobs losses in the New York alone. The cost of currency hedges—and thus "certainty what importers and exporters' money is worth"—has nothing to do with volatility whatsoever, as this cost is exclusively determined by the interest rate differental between two currencies. Nevertheless, as Tobin said, "If ... [currency] is suddenly withdrawn, countries have to drastically increase interest rates for their currency to still be attractive." Is there an optimum tax rate? Financial transaction tax rates of the magnitude of 0.1%-1% have been proposed by normative economists, without addressing the practicability of implementing a tax at these levels. In positive economics studies however, where due reference was paid to the prevailing market conditions, the resulting tax rates have been significantly lower. For instance, Edwards (1993) concluded that if the transaction tax revenue from taxing the futures markets were to be maximized (see Laffer curve), with the tax rate not leading to a prohibitively large increase in the marginal cost of market participants, the rate would have to be set so low that "a tax on futures markets will not achieve any important social objective and will not generate much revenue." Political opinion Opinions are divided between those who applaud that the Tobin tax could protect countries from spillovers of financial crises, and those who claim that the tax would also constrain the effectiveness of the global economic system, increase price volatility, widen bid–ask spreads for end users such as investors, savers and hedgers, and destroy liquidity. Tobin