Since the measles outbreak in the United States is only getting worse, and since most of the people who get measles have not been vaccinated, much of the discussion surrounding this outbreak has focused on parents who do not vaccinate their children. The argument has been framed as one of parental choice, as New Jersey Gov. Chris Christie (R) put it in comments he quickly walked back on Monday.

All of which raises the question: How do Americans actually feel about vaccinations and whether parents should have a choice in the matter? The answer, it turns out, is that most Americans believe vaccinations should be mandatory, but you are significantly more likely to feel that way if you actually lived through a time when measles were a widespread danger, rather than a resurgent threat.

A report from the Pew Research Center last week showed that about seven in 10 Americans feel that parents should have to vaccinate their children. On Monday, Pew released additional figures, showing the breakdown by age group.

It turns out that people between the ages of 18 and 29 are more likely than the American public to think parents should get to decide what to do with vaccinations. Four out of 10 Americans in this age group feel that way (41 percent), compared to three out of 10 Americans nationally (30 percent).

This gulf is even more pronounced if you compare it with older generations. Americans older than age 50 are about half as likely as millennials to say that parents should get to decide whether to vaccinate their kids, with just a fifth of those Americans expressing that view (23 percent of those age 50 to 64 and 20 percent of anyone older than that).

The likeliest explanation here is simply that people are speaking to their experiences. A 29-year-old would have been entering high school when measles were eliminated in the United States and may have never met anyone who has contracted the disease; a 65-year-old was about to enter high school when the measles vaccination became widespread in 1963.

It is also important to remember that until this vaccination became routine that year, between 3 million and 4 million people were infected every year, and between 400 and 500 of those people died, according to the Centers for Disease Control and Prevention. The disease was deemed eliminated in 2000, and since that time most years have seen measles cases that numbered in the dozens (until outbreaks last year and this year).

Meanwhile, the Pew numbers also helpfully fact-check what seems to have become a misconception surrounding the ongoing anti-vaccination movement — that its proponents are all upper-class, well-off people. Pew reported almost no difference in opinion between people with college degrees and those without, as well as similar viewpoints from those making under $30,000 a year and those making more than $75,000 annually.

The breakdown is below: