Although oddly the country also has a higher-than-average suicide rate. But half what it was a decade or so ago. The Finns are supposed to be an introverted bunch - I was once told that the Swedes have a joke about their neighbours:

'How can you spot an extroverted Finn?

They look at your shoes instead of their own when they talk to you.'

But yeah, I think the education system must have a lot to do with it: late start, small sizes, but above all autonomy given to schools and teachers to accommodate their students' needs, rather than forcing them through a one-size-misfits-all sausage machine, resulting in lifelong anxiety and trauma for many, as is the norm in most countries.