Here's an interesting finding from Alexander Bick and Nicola Fuchs-Schündeln* (PDF)—in every country, married men work more hours per year than single men. And in almost every country, married women work fewer hours than single women. But there are four exceptions to that trend and they're all adjacent to one another. In Sweden, Denmark, Norway, and Finland, married women work slightly longer hours than the single ladies.
These gendered labor supply differences across countries are a huge driver of gaps in GDP per capita but they're not much discussed by politicians or political pundits. Bick & Fuchs-Schündeln* suggest that the behavior of Swedish and Norwegian women can be explained by a general model of tax effects, but that this doesn't really work for Denmark and Finland. Resorting to "culture" in a context like this is a cop-out, but there's a larger context of very strong gender egalitarian norms at work throughout this region that is obviously in play here.
*Correction, June 27, 2013: The last name of Nicola Fuchs-Schündeln was initially spelled incorrectly in this post.