Should we be worried about America’s growing national debt, now at $22 trillion? That figure represents a debt-to-gross domestic product (GDP) ratio of 106 percent. By historical standards, that’s a level not seen since the end of World War II, when the 1946 ratio reached 119 percent.

Budget hawks predict doom given today’s figures, while the White House and Wall Street sound like Mad Magazine’s Alfred E. Neuman: “What, me worry?” The doves contend that other nations, notably Japan, have far higher debt ratios, and they seem OK. Who’s right?

Our national debt exceeds more than we produce annually as a nation. In 1946, we’d just spent nearly six years fighting fascism in Europe and Asia. Thereafter came what the French call the “Thirty Glorious Years,” which brought rapid economic growth and rising prosperity, innovation and productivity gains, plus relative peace, notwithstanding a Cold War.

The U.S. emerged as the dominant economic and political power, with the U.S. dollar becoming the main global reserve currency. Our debt-to-GDP ratios subsequently fell to postwar lows of 31 percent in 1974, 1979, and 1981. Thereafter, they resumed an upward trajectory that many today consider dangerously unsustainable.

Japan has the world’s third largest economy, and its debt-to-GDP ratio reached 253 percent this year. So why aren’t more people worrying about Japanese debt? Like the U.S., Japan issues debt in its own currency, maintains flexible exchange rates, and has a strong, proactive central bank.

The principal difference lies in the fact that Japanese debt is financed internally: approximately 90 percent of Japanese bonds are held domestically, compared with less than 60 percent of U.S. Treasury notes being held by U.S. individuals and financial institutions. This fact means that the U.S. remains more exposed to global threats and pressures that can affect our economy.

Additionally, while the Japanese yen remains an important reserve currency, it is not the principal reserve currency used to settle major transactions around the world and, most notably, in the sale of key commodities such as oil. The majority of foreign reserves is also held in U.S. dollars.

Former French president Valery Giscard d’Estaing quipped in 1965 that the outsized role of the U.S. dollar in global economic affairs conferred an “exorbitant privilege.” Giscard was both correct and envious.

This “exorbitant privilege,” plus the fact that currencies today float against each other without a fixed exchange rate, means that these “fiat currencies” are backed primarily by each country’s full faith and credit. What was once secured by gold is now secured by political rhetoric and political credibility.

This privilege has its plusses and minuses. We appear to have a limitless credit card based on our ability to borrow in our own currency and, whenever necessary, print whatever money we need. But that fact has also enabled us to live far beyond our means. To their credit, the Japanese are now pursuing a budget surplus; for the U.S., facing trillion dollar annual deficits once again, a surplus is nowhere in sight.

Japan’s example is not worth emulating: there’s been a lost decade (or more) of economic growth, reduced prosperity and innovation, and a declining population. Another country with a dangerously high debt-to-GDP ratio is Greece, at 181.1 percent. That’s not a viable model either.

Once upon a time, the United Kingdom held the world’s principal reserve currency, a fact often forgotten in today’s budget debates. Exhausted by war and the rising costs of maintaining a global empire, the U.K. finally ceded authority to the Americans: since the 1944 Bretton Woods Agreement, the dollar, not the pound sterling, has been the king of global currencies.

The British example is worth careful study. It’s not written in stone that the U.S. dollar will enjoy forever its exorbitant privilege. Already there are efforts afoot to reduce reliance on the U.S. dollar in favor of more diversified approaches such as a weighted market-basket of key currencies or special drawing rights engineered through the International Monetary Fund.

The Japanese economy will muddle along while managing declining growth, prosperity, and population. But it’s really the U.S. and Chinese debt situations that bear watching. While China’s debt-to-GDP ratio is a modest 50.50 percent, its overall level of debt (corporate, household, and government) is $40 trillion, or 303 percent of GDP. In the U.S., the comparable figure is a whopping $75.3 trillion, or 365 percent of GDP.

Debt-driven prosperity is a fleeting illusion. Those who believe otherwise should revisit economic history.

Charles Kolb was deputy assistant to the president for domestic policy in the George H.W. Bush White House from 1990-1992. From 1997-2012, he was president of the nonpartisan, business-led think tank, the Committee for Economic Development.