I don't think there is much to subjective measures of happiness. Looking at things like GDP, life expectancy, access to education, and other important objective variables, is more scientifically meaningful.
I doubt it.
I wonder if, upon being asked, a Dane would answer that yes, they are happy. Obviously, everything you mention above is important, But I also wonder if Danes are not culturally driven to say "yes". Maybe it's a factor in their national identity to consider themselves satisfied.
If happiness is an objectively truth, then the wealthy will be the happiest just about anywhere in the world, after all, they have access to the best education, health care, trips to Tahiti, etc., and can provide that for their loved ones.
But sorry, this is not what I see. I see the wealthy taking Prozac, whining incessantly, going to shrinks, committing suicide, etc.
And then I see cheerful, carefree, satisfied people in slums in Rio. I know, hard to believe, you'd say, but it's true. People who are delighted with just being alive, all smiles, and if you ask, they'll say they're the happiest on earth. If you probe, oh yeah, they have a chronic illness that was never looked into, the kid has dropped school to go to work, but it could always be worse, right? So they feel happy. I talk to happy janitors all the time.
So while it's undeniable that wealth and health care and education are essential to happiness, national identity, in my humble opinion, can be a factor.