What A Problematic National Debt Looks Like

In Nigeria debt service, mostly domestic, took up a staggering 96% of government revenues last year.

From here. This said, Nigeria's debt is only about 38% of the GPD. But it pays higher interest rates than the U.S. does and collects less government revenue as a percentage of GDP.

Apparently, in Nigeria (according to the source for the quote): "Part of the problem is that the government has collected little money from oil recently due to rampant oil theft, low production and the cost of fuel subsidies, which are deducted before oil proceeds reach the treasury."

By comparison, the U.S. federal government spends 13% of total federal spending as of April 2023 (about $460 billion per year) on debt service for the U.S., federal government's debt. The U.S. national debt is about 120% of the nation's GDP.

The biggest issue in the U.S. is that the interest rates that the U.S. government pays on the national debt are very low and if they increase significantly, the debt service costs could increase greatly.