The Gallup-Healthways Well-Being Index asks 500 U.S. adults each night whether they had the flu or a cold "yesterday." Those sick with the flu or a cold may be less likely to respond to a phone survey, so these percentages might underestimate the actual prevalence of illness, Gallup said.
The national flu average remained steady in 2013 at 2 percent, slightly below the high of 2.2 percent recorded in 2008.
Vermont, North Dakota and South Carolina had the lowest flu rates, with each averaging less than 1 percent.
Florida, Texas and New Mexico ranked among the top 10 states for five out of the last six years. These states also have high percentages of residents who lack health insurance, which may make it more difficult for residents to afford flu shots, Gallup said.
Additionally, these states, as well as New York, Arizona, and New Jersey, have some of the largest Hispanic populations in America. Gallup found that Hispanics are more likely than any other major demographic group to report being sick with the flu and the most likely subgroup to lack health insurance. Hispanics also were hit harder with the H1N1 (2009) pandemic.
More than 8 percent of Montana residents were the most likely to report being sick with a cold on any given day, with Oregon at 7.7 percent, New York at 6.9 percent and Mississippi at 6.9 percent. Cold rates were lowest in Arizona at 3.8 percent, followed by Kansas and Wyoming -- both at 4.2 percent.
The telephone survey was conducted as part of the Gallup-Healthways Well-Being Index survey Jan. 2-Dec. 29, 2013, with a random sample of 178,068 U.S. adults. Its margin of error ranges from 1 percentage points to 2 percentage points for large states and 4 percentage points for small states such as Wyoming, Delaware and Hawaii.