MELBOURNE, Australia — In international rankings, there’s a club of usual suspects that more often than not does really well. Finland and other Nordic nations often come out on top, be it in quality of life, education or health care. On the other side of the world, New Zealand and Australia appear to have become members of that exclusive club, too, while the United States consistently misses out.

When the United Nations released its annual World Happiness Report last year, these usual suspects made it to the top 10 once again. But more surprisingly, they also led in another, less favorable recent statistic: the ratio of citizens affected by mental health disorders. A separate 2017 study by the World Health Organization concluded that, other than Americans, Ukrainians and Estonians, citizens of Australia were more likely to develop depression than people living anywhere else in the world. Other strongly affected nations included New Zealand and Nordic states such as Finland and Denmark.

Studies with a slightly different research focus or methodology have observed similarly severe or even worse mental health issues among children growing up in poorer countries such as India, and it is likely that mental health issues are substantially underreported in many developing nations.

But the mental health crisis that increasingly appears to affect young people from wealthier countries has baffled scientists more than other findings that could be explained by inequality or poverty. Australia became the latest country to announce new efforts to combat the growing problem this week, promising Wednesday to fund mental health programs for young people with an additional $34 million.

“I want our young people to know they are not alone on their journey,” Health Minister Greg Hunt said, according to a government news release.

Researchers acknowledge that the reasons young people are increasingly anxious or depressed are still not fully understood, but recent studies have cited the use of social media and perceptions of not being able to fulfill unrealistic expectations of employers, friends or partners.

Numbers collected by the Mission Australia charity from two years ago already showed a sharp increase in the number of young Australians suffering from mental illness, with about 23 percent of 15- to 19-year-olds impacted. More recently, a government study similarly concluded that about 25 percent of all 16- to 24-year-old Australians are believed to struggle with mental illnesses every year.

"We are talking about an alarming number of young people facing serious mental illness, often in silence and without accessing the help they need,” said Catherine Yeomans, Mission Australia’s then-CEO.

The same trend was reported in Sweden, where young citizens were 20 percent more likely to be prescribed anxiety medications in 2013 than they were in 2006. Meanwhile, Finnish researchers have observed an even more severe jump in the years since then. In Helsinki alone, the number of children being treated for mental health issues more than doubled within a decade. In Sweden and in some of the other Nordic countries, researchers concluded that mounting mental health problems among younger people are resulting in a widening life satisfaction gap between generations.

“People in the Nordic region are generally happier than people in other regions of the world, but despite this there are in fact also people in Denmark, Finland, Iceland, Norway and Sweden who report to be struggling or even suffering,” wrote the authors of the report “In the Shadow of Happiness,” which was released by the Nordic Council of Ministers last year. While 12.3 percent of all Nordic region residents said they were struggling or suffering, that ratio was more than one percentage point higher among 18- to 23-year-olds.

Other researchers caution that growing mental health issues among young people might not be necessarily limited to residents of the nations that perform the best in global statistics, such as Australia and Finland. They say that respondents in countries such as Australia, Sweden and Finland — where access to health care is relatively easy — may be simply more likely to self-report signs of mental illness, skewing the comparability of those rankings and perhaps hiding a more global trend.

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