These statistics are worthless. Slovenia and Japan make the list while having enormous suicide rate, bigger than my country (Poland, not listed). What the heck? I bet that the average citizen of Bhutan, Micronesia or Philippines is more happy than average European with debts, work pressure, noise and all the disadvantages of living in a big city.
Ask the people who made the survey about the factors. I can say that Japan has history behind it's suicide rates. Suicide used to be honorable under some circumstances, especially for samurais and generals.
There may also be some survivor bias. If someone is unhappy enough to commit suicide, they won't be able to fill out surveys about how unhappy they are.