In addition to exemptions for the tax and paid by businesses, governments may also attempt to induce saving amongst their populations as a method of increasing the availability of investment capital. One particularly extreme example of this comes from Japan's postal savings system, where individuals were incentivized through tax breaks to place funds in the system, which were then available to the state for economic policy purposes. Indeed, at one point, funds within the postal savings system were, according to Heidenheimer et al. (ibid.: 149), four times the size of the world's largest commercial bank (the bank of America).