This is my source: https://www.populationpyramid.net/united-states-of-america/2...
As you can see, the percentages for each age group are close to each other, meaning it's more even.
As you can see, the percentages for each age group are close to each other, meaning it's more even.
Also, on the graph you linked to, you can click on the line in the graph of population versus year to the right, and if you start back in the 1950s and work your way along to the present, you can see the big lump of the baby boomers getting older. That's why people say the United States has an aging population.
So yeah, that graph shows the US is, on average, getting older. Immigration helps patch the numbers a bit, but the US immigration system attracts older candidates than most.