In normal times the financial performance of central banks tends to draw little attention. No wonder. A central bank is a not-for-profit public institution that technically cannot be declared insolvent as it can, due to its monopoly on currency issuance, always create the liquidity it requires.

These are not normal times. As with other aspects of central banking, the crisis has placed their balance sheets under the spotlight. In many places, the crisis has highlighted a need for extra reserves