A Harris Poll of 2,345 U.S. adults surveyed online April 10-15 by Harris Interactive found certain groups, such as minorities, recent graduates and the disabled, trended downward in the last couple of years.
"Our happiness index offers insight into what's on the minds of Americans today and is a reflection of the state of affairs in our country," Regina Corso, senior vice president of the Harris Poll, said in a statement. "While the attitudes on the economy may be improving, we're seeing that this is not translating into an improvement in overall happiness."
Since last measured two years ago, the Happiness Index was especially low among the Hispanic-American population. It is important to note that a causal link cannot be established, it might not be a coincidence that this drop coincides with a political landscape that has seen frequent, sometimes contentious, discussion of immigration policy in recent months, Corso said.
Americans earning under $50,000 per year were less likely to qualify as very happy than in 2011 -- down from 33 percent to 29 percent among those earning less than $35,000, and from 35 percent to 32 percent among those earning between $35,000-$49,999.
Those 50 and older were more likely to be very happy than younger people.
Thirty-two percent of political independents were less likely to qualify as very happy than members of either the Democratic or Republican parties at 35 percent each.
No margin of error was provided.