The Gallup's Health and Healthcare also found despite the decline, 40 percent still rated their coverage as good and 27 percent as excellent.
Americans are much more positive about their own healthcare coverage than about healthcare coverage in the United States in general.
The poll, conducted Nov. 15-18, found 41 percent rated U.S. healthcare coverage as excellent or good and a combined 58 percent said their coverage was only fair or poor.
Higher-income U.S. adults were much more likely than lower-income adults to rate the quality of their healthcare and their healthcare coverage as excellent or good. However, even a majority of the lowest-income Americans rate both highly, Gallup said.
Medicare and Medicaid recipients and those with private health insurance are about equally likely to give their healthcare coverage and quality good ratings.
The telephone survey of 1,015 U.S. adults has a margin of error of 3 percentage points.