Reported contentment in the U.S. declined from 2005-2007 to 2013-2015, according to the latest World Happiness Report. It's unclear if we can make America happy again.

The U.S. came in 93rd out of 126 countries ranked by changes in national effervescence. The countries that are "most happier" today include Nicaragua (1), Ecuador (3), Russia (10), and China (19). The tipping point is at Australia (70) and Austria (71), which show practically no change. The deepest downturn? Well, Greece.

The drop in well-being is a more interesting measure than the happiness ranking itself, though that's what the report focuses on. There's not much drama anymore in revealing, say, which Western European social democracy feels best about itself (Denmark Out-Glees Switzerland for 2016 Title). For your information, the U.S. shot up two places, to number 13.

"The U.S. numbers have gone down" as measured by change, said John Helliwell, a University of British Columbia economist and lead author of the rankings, "but Costa Rica and Mexico have fallen by more."

The report, organized by the United Nations Sustainable Development Solutions Network, is an analysis of Gallup World Poll data generated from surveys of 1,000 people in each country every year for three years. The researchers defined six categories that seem to explain about 75 percent of the survey data. They are gross domestic product (a nation's output of goods and services) per capita, social support, healthy-life expectancy, personal freedom, charitable giving, and perceived corruption.

The authors account for any difference between the data and the six-point theory of happiness by combining each country's discrepancy with a baseline misery index, conjured into an imagined rock-bottom country they playfully call Dystopia.

This year, the team introduced a new snapshot of inequality, a measure of the happiness gap within a country. Bhutan, whose king coined "gross national happiness" in 1972, had the most even distribution of well-being. But equality doesn't necessarily translate into countrywide giddiness; Bhutan landed 84th of 157 on the main happiness ranking, right under China, just like in real topographic life.

The U.S. has inequality of well-being to match its much-discussed income gap. Americans are 85th among 157 countries ranked by their spread between the most and least happy.

This year's report is an interim assessment before the researchers issue a deep dive next year. That report will look more closely at workplace happiness and the effects of immigration and refugees on aggregate happiness.

Happiness and parenting is the subject of a study included in an addendum to the report. Many previous researchers have remarked that happiness graphed over a lifetime tends to follow a U shape: Youth is great, parenting is hard, retirement rocks. This finding has been studied widely, notably by the University of Warwick's Andrew Oswald, who showed it holds in chimps and orangutans and anybody with kids.

The new work shows that parenting is hardest on those in high-GDP countries, and particularly among the unemployed. Why that should be is the subject of further study, according to Luca Stanca, an economist at the University of Milan-Bicocca who conducted the parenting research. It's easy to understand how unemployment plus mouths to feed is a recipe for hardship, but unhappier parents in countries with high GDP?

Stanca suggested, pending further study, that perhaps parenting in richer nations carries a greater opportunity cost than in poorer ones -- there's more to do, and greater economic and social reward for doing it. A kind of child-rearing fomo, then. The effect is stronger for women and eases for both men and women as they grow older.

"This is how I started to be interested in this topic," Stanca said. "I had three daughters, and then I had twins, and I started wondering..."