This paper titled "Why Danes are smug: comparative study of life satisfaction in the European Union" published in the British Medical Journal, investigates the phenomenon of why the Danish are always so happy.

The paper includes this graph showing the percentage of survey respondents who admit to being very satisfied with their life. The Danes consistently come out on top (BTW, what's up with Portugal?):

The authors posit a number of reasons for why the Danes are so much happier than the rest of Europe:

1. Hair colour
   
2. Genes
   
3. Food
   
4. Climate
   
5. Native tongue
   
6. Alcohol and smoking
   
7. Marriage and children
   
8. General health
   
9. Welfare state
   
10. Exercise
    
11. Prowess in sports
    
12. Expectations
    

The article is written in what starts out as serious tones and ends up sounding like one of Preston McAfee's "tounge-in-cheek, but hey there is something important here" pieces. It is hard to tell if the journal and the article are meant to be taken seriously - I leave it to the reader to decide. The article concludes:

The causes of the stolid depth of Danish wellbeing are undoubtedly multifactorial. We are satisfied, however, that in the end and against all odds we have contributed to comprehension of the conundrum of Danish contentment. We doubt that further research would lead, in the foreseeable future, to deeper understanding, but decades of effort might possibly result in some incremental advance. Optimism is unwarranted.

Our analysis points to two explanatory factors. The Danish football triumph of 1992 has had a lasting impact. This victory arguably provided the biggest boost to the Danish psyche since the protracted history of Danish setbacks began with defeat in England in 1066, followed by the loss of Sweden, Norway, Northern Germany, the Danish West Indies, and Iceland. The satisfaction of the Danes, however, began well before 1992, albeit at a more moderate level. The key factor that explains this and that differentiates Danes from Swedes and Finns seems to be that Danes have consistently low (and indubitably realistic) expectations for the year to come. Year after year they are pleasantly surprised to find that not everything is getting more rotten in the state of Denmark.

This is the type of research I want to perform.