Me thinks the numbers won't be so bad if you add splinter green and left parties, although there is a real shift of social democrats to traditionally liberal economics in Europe.
I did a quick skim of results. Social Democrats are bleeding voters in three streams
1) Communist/Hardline socialist parties. e.g. Socialist Party of the Netherlands, Die Linke etc.
2) "Bourgeois" green or left-liberal parties. e.g. D66, Alliance90/Grunen, Parti Vert.
3) Anti-immigrant/far right parties e.g. PVV, Front Nationale
So, while the numbers are much better for left wing parties as a whole, there is still a leak to the far-right.
