1980s. Japan's high personal savings rates, driven in part by the demographics of an aging population, enabled Japanese firms to rely heavily on traditional bank loans from supporting banking networks, as opposed to issuing stock or bonds via the capital markets to acquire funds. The cozy relationship of corporations to banks and the implicit guarantee of a taxpayer bailout of bank deposits created a significant moral hazard problem, leading to an atmosphere of crony capitalism and reduced lending standards. In so doing they helped inflate the bubble economy to grotesque proportions." The Bank of Japan began increasing interest rates in 1990 due in part to concerns over the bubble and in 1991 land and stock prices began a steep decline, within a few years reaching 60% below their peak. Economist Richard Koo wrote that Japan's "Great Recession" that began in 1990 was a "balance sheet recession". It was triggered by a collapse in land and stock prices, which caused Japanese firms to become insolvent. Despite zero interest rates and expansion of the money supply to encourage borrowing, Japanese corporations in aggregate opted to pay down their debts from their own business earnings rather than borrow to invest as firms typically do. Corporate investment, a key demand component of GDP, fell enormously (22% of GDP) between 1990 and its peak decline in 2003. Japanese firms overall became net savers after 1998, as opposed to borrowers. Koo argues that it was massive fiscal stimulus (borrowing and spending by the government) that offset this decline and enabled Japan to maintain its level of GDP. In his view, this avoided a U.S. type Great Depression, in which U.S. GDP fell by 46%. He argued that monetary policy was ineffective because there was limited demand for funds while firms paid down their liabilities. In a balance sheet recession, GDP declines by the amount of debt repayment and un-borrowed individual savings, leaving government stimulus spending as the primary remedy. Economist Scott Sumner has argued that Japan's monetary policy was too tight during the Lost Decades and thus prolonged the pain felt by the Japanese economy. Economists Fumio Hayashi and Edward Prescott argue that the anemic performance of the Japanese economy since the early 1990s is mainly due to the low growth rate of aggregate productivity. Their hypothesis stands in direct contrast to popular explanations that are based in terms of an extended credit crunch that emerged