Indeed, investors in the iShares MSCI Mexico Investable Market Index Fund (NYSEArca:EWW) saw a 16.29 percent return in the first quarter, much of it on the back of the Mexican peso. Should the U.S. economy begin to slow down, a correction in the peso will undoubtedly draw back returns for investors in EWW. The peso's strength is largely due to the steady hand of Mexico's central bank, which has kept inflationary pressures at bay, as IndexUniverse's Currency Impact Report shows.