Denmark is the happiest country in the world, followed by Norway, Switzerland, the Netherlands, and Sweden, according to the 2013 World Happiness Report, released today by Columbia University's Earth Institute.

Sponsored by the United Nations Sustainable Development Solutions Network, the global survey took place between 2010 and 2012 and ranked the happiness levels of people in 156 countries, using such criteria as wealth, health, freedom to make life choices, having someone to count on in times of trouble, freedom from corruption, and the generosity of fellow citizens.

The U.S. came in 17th overall in the happiness stakes, just behind Mexico, while Britain finished in 22nd place, Russia in 68th, China a gloomy 93rd, and Iraq 105th. War-torn Syria came in an unsurprising 148th place, while a handful of West African countries seemed to be unhappier still, with Benin at 155th and neighboring Togo bringing up the rear at 156th.

According to the UN report, there are some common themes in the happiest places on Earth, including:

1. It (mostly) pays to be rich.

This may be the obvious one. Money may not buy happiness, but it sure doesn't hurt, as even the most cursory glance down the list of the world's happiest countries reveals. They are all expensive places to live.

They also have high taxes, spend a lot of money on social welfare programs, and enjoy good health care. There are no wars in these places. Or malaria. And very little corruption.

2. More money means more problems.

On the other hand, warns Jeffrey Sachs, the director of Columbia's Earth Institute and one of the authors of the report, riches can cause stresses and problems of their own. In his introduction to the report, Sachs cites the "persistent creation of new material 'wants' through the incessant advertising of products using powerful imagery and other means of persuasion."

Sachs warns that an advertising industry worth around $500 billion per year is "preying on psychological weaknesses and unconscious urges," and therefore making us less happy. Unhealthy products like cigarettes, sugar, and trans-fats are being pushed to our detriment, he wrote.

Such stresses and disillusionment may account for why the overall happiness figures for the (otherwise happy) industrialized West have been declining, while countries in developing regions, especially in Latin America and sub-Saharan Africa, have been becoming happier overall, Sachs noted. Of the three biggest gainers in overall happiness, two (Angola at 61st and Zimbabwe at 103rd) were in Africa. Albania (at 62nd) is the third.

3. Being poor in Europe can be particularly rough.

Bulgaria may be a member of the European Union, but it is by far its poorest member and is burdened by endemic corruption. A recent poll showed that as much as 5 percent of the population is planning to leave their homeland and emigrate, mainly to the U.K. and Germany.

Bulgaria's unhappiness quotient, as measured by the survey, puts the country in a deeply unhappy 144th place—behind Afghanistan (143rd), Yemen (142nd), and Iraq (105th). Even Zimbabweans, whose country has endured an average inflation rate of nearly 1,200 percent for the past decade, seem considerably more contented than Bulgarians, coming in at 103rd on the list.

4. Nice weather doesn't correlate to happiness.

Forget palm trees and crystalline beaches, azure seas, and thoughts of plump mangoes falling into your lap—such things may be okay for holiday dreaming, but lovely weather doesn't seem to cut it when it comes to making us happy on a day-to-day basis.

With the lone exception of Australia (coming in at number 10), all of the world's top-ten happiest countries have long, bleak winters. Iceland, which edges out Australia at number 9 on the list, barely sees the sun at all. In contrast, Mauritius, a favorite honeymoon and holiday destination for the happy folk of northern Europe, is at 67th on the happy list, and Jamaica in the sunny Caribbean languishes in 75th place.

5. Happy people ride bicycles—by choice.

Denmark and the Netherlands (the happiest and the fourth-happiest countries on Earth) are renowned for being the world's most bicycle-friendly nations; the other most-happy countries are also famously bicycle friendly. To be sure, much of the developing world gets about by bicycle, as does economic powerhouse China, but not, it seems, because they want to.