Public schools may be suffering, but the private tutoring business—a $5 billion industry—is growing like gangbusters, The Week reports. Times may be tough for many Americans, but, as the quality of public education grows shakier, it still pays to be a tutor—or at least a corporate tutoring firm. While the rest of the economy has sputtered and stagnated, the “supplemental education” sector has grown tenfold over the last decade. Here, a brief guide, by the numbers to “America’s tutor boom” [1]: $5 billion-Estimated size of the “supplemental education” [1] sector…