People who rather to kill themself than others
People from Northeast Asia and North Europe are more likely to kill themself than other people.
Less sunlight? Nope. Singapore Chinese, New Zealand and Australia whites are living in region with most sun light (high melanoma rate). Yet they still have simlar pattern as their ancestror land.
Countries with high suicide/low homocide pattern are mostly developed countries except China. If China become rich country, then every thing will be consistent.
Ability to plan and predict future is critical to forecast future suffering and hopeless outcome. When people realize the future unbearable suffering with no hope, ending your own life is end of suffer.
If one is agnostic about future, one will not kill himself.