Despite the financial crisis, a beer a day is deemed 'necessary' by Spaniards, according to a poll reported on in Think Spain: Not without my beer.
Apparently, the Spanish are cutting back on travel and eating out, but having a beer in the evening is not something they are willing to forego (a fact wonderfully sent up in this article Denounce the Reign in Spain).
It may surprise you, considering the fact that there is so much good Spanish wine and that the Spanish make the perfect gin and tonic,†that they'd value the humble beer so much, especially when you see how humble most Spanish beers are - gassy, pale and lacking much flavor. But it's true - beer is everywhere in Spain, taken at all times of day (I've seen it on occasion offered as a breakfast offer with a slice of tortilla) for any occasion.
It's not actually impossible to find good beer in Spain, but it is difficult. Read my tips on getting the the amber nectar when in Spain: Beer in Spain
See also: Best Drinks in Spain