Are we looking at the same chart like? Because that chart shows it's been roughly steady since 1990, with some peaks up and some peaks down: 1991 was an outlier upwards, 2012 an outlier downwards, but overall: roughly stable. This kind of variation is to be expected since in absolute numbers it's a relatively small number of people.
> Compare to Finland which has a similar fall, but continues to fall instead of rise.
Just minutes ago in another comment you yourself posted a link which clearly and markedly shows that Finland has seen a marked and steep rise in the last few years: https://news.ycombinator.com/item?id=38339299
