Why have below-growth interest rates in OECD countries not led to a huge increase in debt?

In OECD countries, interest rates on debt (including the risk premia paid by the various borrower classes) have been lower than the growth rate since 2013, except for High Yield bonds. This would normally be expected to have driven up debt ratios sharply, but this has not been the case . How can this be explained? We can imagine that: Borrowers do not believe that interest rates are going to remain so low for long; Even though bond interest rates are very low, borrowers still need to repay the stock of debt. Beyond a certain level of debt, very low interest rates therefore do not drive up debt any further; Asset prices have hardly risen , because risk premia on asset valuations are very high, which means that the value of collateral used to borrow has hardly risen.