Happiness in Sweden
Happiness in nations is measured in survey studies using questions such as “Taking all together, how satisfied are you with your life-as-a-whole these days?”. Responses to such questions are gathered in the World Database of Happiness . The section Happiness in Nations  of that database presents all the findings in general population samples in nations. The following reports are derived from this source:
Overview of findings on happiness in Sweden
The available findings are presented in the latest ‘Nation Report’ on Sweden .
This report is ordered by type of happiness questions and within these types by year. This ordering is to facilitate the assessment of progress, comparison over time being most fruitful using the same questions.
The report presents means and standard deviations, both on the original scale range and transformed to a common range 0-10. The means inform about the level of happiness in the country and the standard deviations about inequality of happiness.
Links provide more detail about the precise text of the question, the full distribution of responses and technical details of the survey. The report is continuously updated.
Rank relative to other nations
Comparison with happiness in other countries is facilitated by ‘Rank Reports’. These reports limit to the measure of happiness that is available for most countries, that is, questions on satisfaction with life-as-a-whole rated on a 0 to10 numerical scale. Four rankings are derived from responses to that question:
1) Average happiness (mean score) 
2) Happy Life Years (average combined with life expectancy) 
3) Inequality of happiness (standard deviation) 
4) Inequality Adjusted Happiness (combination of mean and standard deviation) .
These four indicators are discussed in the paper Measures of Gross National Happiness .
Progress in happiness over time
Comparison over time is facilitated by ‘Trend Reports’. These reports limit to measures of happiness on which at least 10 data points are available over a period of at least 20 years, since this is typically required for identifying a trend over time. These Trend Reports provide not only a view on progress in happiness in this nation but also allow comparison with progress in other countries.
Unfortunately there are no trend reports available yet for Sweden.