Eric Weiner traveled all over the world in search of answers to the questions: Which countries have the happiest people and why? His answers surprised him and they surprised me too. Based on research, Iceland comes out towards the top of the pile, and Saudi Arabia towards the bottom.

But the best predictor of happiness is trust. If people trust the people around them, friends, and family, and if they trust their government, then they will score highest on the happiness surveys.

https://www.blog.theteamw.com/2011/03/05/100-things-you-should-know-about-people-72-trust-is-the-best-predictor-of-happiness-2/