Notwithstanding a dalliance with property in the mid-2000s, Ireland’s economic model has been consistent for the last sixty years: Ireland is a European base for American companies. The model was set up in the 1960s, but it wasn’t until the ’90s that it started to really bear fruit.  Two things changed in the 90s. First, American firms started thinking globally. They spent a lot of money going after overseas markets.  Second, in the 1990s the nature of business started to change. Instead of selling stuff — like cars, chemicals and turbines — companies started selling ideas. Ideas can take the…