A “best case” scenario of US pension funds seeing a 25% return on investments would reduce pension liabilities by only 1% through the end of 2019, according to a new report form Moody’s investor service.

And the “base case” scenario of 19% returns? That would see liabilities rise by 15%.

“For many states and municipalities, exposure to unfunded pension liabilities is already at or near all-time highs. Since cost burdens are already expected to further increase, pension fund investment performance is critical for the credit quality of many governments,” Bloomberg quoted the report as saying.