Three years ago, €4.30 of every €100 that passed through the tills at Carraig Donn was left over after wages, rent, energy and other operating costs were paid. Today that figure is closer to €2.60, and these profit margins are consistent across Irish retail. With transaction numbers holding up, this 40% decline has happened without a collapse in footfall. That’s the paradox at the heart of the Irish retail puzzle. The headline economic data says Irish consumers are still spending, yet the insolvency data tells us that retailers are failing at the fastest pace seen in years.  Mark Degnan, a…