Thais are less happy than last year, while Finland tops the rankings in the United Nations' World Happiness Report 2018 published on Wednesday.
In this year's report, a survey of the state of global happiness, Thailand dropped from No.32 in 2017 to No.46 this year. Among, the 10 Asean members, Thailand is ranked behind neighbours Singapore (No.34) and Malaysia (No.35).
Thailand mustered 6.424 on last year's happiness index, a score that fell to 6.072 this year.
When asked about the new ranking, Thai government spokesman Sansern Kaewkumnerd said he has not seen nor studied the report yet, but added that "The rank can go up and down."
Finland switched places with last year's winner Norway who came in at No.2 among 156 countries, with Europe's Nordic nations having dominated the index since it was first introduced in 2012.
Although swapping places, the top 10 positions have been held by the same countries over the past two years, namely Denmark, Iceland, Switzerland, the Netherlands, Canada, New Zealand, Sweden and Australia.
The United States fell to 18th place from 14th last year.
Released by the Sustainable Development Solutions Network for the United Nations on March 14, the rankings are based on the pooled results from Gallup World Poll surveys from 2015-2017.
The countries on the report were ranked on six key variables that support well-being: income, freedom, trust, healthy life expectancy, social support and, generosity.
This year's report also focused on migration within and between countries, it evaluated 117 countries by the happiness and well-being of their immigrants, with Finland also ranked at number one.
Finland's ambassador to Thailand, Satu Suikkari-Kleven, said she was happy her country was ranked at No.1 on both the general Happiness Index and Immigrant Happiness.
"I think the reason Finland is at number one is because of our clean environment, strong social security system, and equality of opportunity which all contributed to happiness of the people," she said.
Meanwhile, the Thai population has risen to 66.1 million as of Dec 31 last year, from the 65.9 million recorded at the end of 2016, according to figures released by the Department of Provincial Administration.