6%, I could buy that, assuming the number is licensed legal carry. In some places it will be higher, much higher but the zeros, in places like you mention bring the average down.
That's about 6% of the population but more like 10% of the adult population. More than 10% when you factor out convicted felons, geriatrics in the nursing homes, mentally ill, etc. Even more with those who use "Constitutional Carry" laws.
18 years and over = 209,128,094
Male =100,994,367
Female =108,133,727
21 years and over =196,899,193
Via Wikipedia: As of November 1, 2019, Alaska, Arizona, Arkansas, Idaho, Kansas, Kentucky, Maine, Mississippi, Missouri, New Hampshire, North Dakota (residents only; concealed carry only), Oklahoma, South Dakota, Vermont, West Virginia and Wyoming (residents only) do not require a permit to carry a loaded concealed firearm for any person of age who is not prohibited from owning a firearm.