The United States is no longer one of the world's ten most "prosperous" countries for the first time according to the Legatum Institute.

The Legatum Prosperity Index assessed and ranked the prosperity of 142 countries based on eight sub-categories: economy, entrepreneurship and opportunity, health, governance, education, safety and security, personal freedom, and social capital.

America experienced an "unprecedented" fall to twelfth in the rankings, as it experienced "weakening performance across five of the Index’s eight sub-categories."

When referring to the U.S., the language of the report had a somewhat dire tone. It claims that "the American Dream is in jeopardy," and "the national ethos of the U.S. is under threat."

The London-based public policy institute pegged the U.S.' precipitous drop to a decline in consumer and voter confidence, along with a bleak economic and entrepreneurial outlook; four percent fewer citizens believe that "hard work gets you ahead," and business startup costs as a percentage of Gross National Income (GNI) have doubled in the past two years.

In fact, the U.S. economy sub-score dropped to twentieth and its personal freedom score dropped four points to fourteenth, just above Uruguay.

“Despite performing relatively well in a few sub-indices," said Jeffrey Gedmin, President and CEO of the Legatum Institute "it is clear that the U.S. is struggling to overcome the barriers to prosperity. Good education alone will not keep prosperity afloat and whoever succeeds in the elections this week needs to address the factors that are holding the nation back from being truly prosperous.”

It appears that Legatum hopes the timing of the report's release — which was made available to the public on October 30 — will have electoral implications in the upcoming presidential race.

“As the US struggles to reclaim the building blocks of the American Dream," Gedmin noted, "now is the time to consider who is best placed to lead the country back to prosperity and compete with the more agile countries that have pushed the U.S. out of the top ten."

Additionally, these rankings represent a yet another shift away from using GDP as the sole metric for measuring prosperity. Gedmin adds: “GDP alone can never offer a complete view of prosperity, which is why, just days away from the presidential elections, the U.S.’s fall in the Index has come at such a pivotal time.”

Last month, the U.N. Settlements program released its own "City Prosperity Index," which ranked a handful of the world's cities according to its own metric determining which were the most prosperous.

Here are the top twenty countries:

Norway Denmark Sweden Australia New Zealand Canada Finland Netherlands Switzerland Ireland Luxembourg United States United Kingdom Germany Iceland Austria Belgium Hong Kong Singapore Taiwan

SEE ALSO: Why the world's most prosperous cities are in Europe »

