A new report shows Taiwan is the happiest among the East Asian countries and ranked No. 33 in the world, and improvement from No. 35 past year.
A new global report measuring contentment based on prosperity, integrity and social support found Vietnamese among the less happy people in the world.
Norway displaced Denmark as the world's happiest country among the 155 countries surveyed.
Central African Republic, Burundi, Tanzania, Syria and Rwanda stood at the bottom of the list.
The U.S. ranked just ahead of Ireland, which took 15th place, and was followed by Germany in 16th, the U.K.in 19th and France in 31st.
The United States was 14th in the latest ranking, down from No. 13 last year, and over the years Americans steadily have been rating themselves less happy.
The six key variables used to measure happiness are GDP per capita, healthy years of life expectancy, social support (as measured by having someone to count on in times of trouble), trust (as measured by a perceived absence of corruption in government and business), perceived freedom to make life decisions, and generosity (as measured by recent donations). "I want governments to measure this, discuss it, analyse it and understand when they have been off on the wrong direction", Sachs said.
"By choosing to produce oil deliberately and investing the proceeds for the benefit of future generations, Norway has protected itself from the volatile ups and downs of many other oil-rich economies", said John Helliwell, one of the authors of the report.
"As demonstrated by many countries, this report gives evidence that happiness is a result of creating strong social foundations".
The U.S.'s happiness has slipped over the past year, however, the report suggests.
Once again, Nordic and Western European countries rule the roost.
Sachs from SDSN said the U.S.is falling in the ranking due to inequality, distrust and corruption.
Unemployment, or the quality of the work they have, is a major factor in people's happiness. And while higher pay clearly makes workers happier, work-life balance, job security, health and safety, social capital and autonomy are also predictive of a higher state of happiness on the job.
Crises that are both severe and long-lasting are often the culprits in countries that saw the biggest decline in happiness from 2005-2007 to 2014-2016. And only two African countries have made significant gains in happiness over the past decade.