10 Facts About Happiness From Around the World On International Happiness Day, find out how personal and professional standing influence a person's mood.

Happiness stems from all aspects of life, from employment to health to friendships. While the building blocks of a satisfying life are universal, happiness levels vary from country to country.

The 2017 World Happiness Report by the UN Sustainable Development Solutions Network reveals which countries are the happiest, ranking 155 countries globally. To measure happiness levels worldwide, the report weighs six key variables: income; healthy life expectancy; social support (having someone to count on in times of trouble); generosity; freedom; and trust.

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The same 10 countries have topped the list over the past five years, although they've shifted positions among one another. European countries top the charts: This year, the report deems Norway the happiest country in the world, followed by Denmark, Iceland and Switzerland. Unfortunately, the U.S. has never been in the top 10, this year falling from 11th to 14th place.

Following are 10 findings about what inspires happiness worldwide.

1. Self-employed people have higher overall life evaluations.

Self-employment has its pros and cons. In developed countries, self-employed people report being more satisfied than those who are traditionally employed. However, they are also more likely to experience negative feelings such as stress and worry.

2. People are happier when they maintain their social life throughout the work week.

Most Americans feel happier on the weekends. But this weekend effect disappears when people work in a "high trust" environment -- where they consider their boss not as a superior but a partner -- and when they take part in social activities throughout the week.

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3. American happiness has been declining over the past decade.

For the past decade, Americans have been reporting lower and lower happiness levels. They associate their decreased satisfaction with having less social support and personal freedom, lower donations and more corruption in business and government.

4. It's important to prioritize your mental health.

Researchers conducted surveys in the U.S., Australia, Britain and Indonesia to uncover the key determinants of unhappiness and misery.

They found that receiving a diagnosis for a mental illness contributes more to a person's happiness than income, employment or a diagnosed physical illness. "In every country physical health is of course also important, but in no country is it more important than mental health," the report states.

While efforts to eliminate poverty and reduce unemployment are crucial, it turns out the most powerful way to decrease misery in the world is the elimination of depression and anxiety disorders (the most common forms of mental illness).

5. Have someone to count on.

People who have partners, solid relationships with extended family or simply someone to count on are much happier than those who do not. The report states that for every 10 percent of a country's population that establishes social support, happiness levels jump by more than 20 percent.

6. Family, childhood and schooling influence happiness later in life.

For adults, happiness levels are largely influenced by one's current economic, social and health status. While backgrounds are often overlooked, they too play a major part in determining overall life satisfaction.

7. Income is more important than education.

Survey respondents from all countries included in the report agreed that income is more important for happiness than education. Some of the wealthiest people in the world are college dropouts, including Mark Zuckerberg and Bill Gates.

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8. Happiness depends on the type of job a person has.

It's no surprise that employed people are happier than unemployed people, but the type of job also comes into play. The report reveals that blue-collar jobs -- in industries such as construction, mining, manufacturing, transport, farming, fishing and forestry -- tend to correlate with lower levels of happiness.

9. It's not all about the money.

Salary isn't the only career aspect that influences one's happiness level. Social status at work, social relationships in the workplace, daily work structure and goal-setting also play major parts in determining happiness levels.

10. Unemployment is "scarring."

Even after a person finds another job, the report explains, the unhappy feelings they experienced while unemployed linger.