Last time I checked, it was estimated 35%, but this is very difficult to say. It was higher 30 years ago (like 50%), and we were in better shape in general. But new technology is helping the tax office to routinely and effectively denounce and extort citizens at higher rates. It is well known that Spain has the worst tax office in the world, half of the time acting illegally, but they are impune to justice.

That's why I think Bitcoin represents a hope for Spaniards. Only if they wake up...