It's hard to tell, in pubs/bars I think our drink is cheaper than it is abroad, but until recently the supermarket prices were the other way round....given those are 2005 data maybe that's the reason?
Also, considering that a lot of the likes of French and Spanish drinkers drink with meals "table wine" which isn't expensive, compared to an Irish requirement of buying "decent" wine - there'll be a 10 euro difference there, anyway.