That’s the problem with averages: you add college courses, get more graduates, increase the total work population, and get a bigger denominator. Of course, the percentage of older programmers will decrease.
Companies have been hiring younger people for years. You really need some sort of mix to utilize industry knowledge other than programming skills. But you are correct, you don’t need that many and most people I worked with could not keep up with technology changes.
I got my last programming job at age 65 and retired at 70 ¼ because I was too cheap to make mandatory IRA withdrawals at the same tax rate as they went in. In the interview, they asked, “Why do you want this job?” I replied, “It sounds like fun.”
Two years later, I was out for surgery. My backup from London covered. When I got back, one dept head sent me this email: “I didn’t know how spoiled I was until you were out.”
This article pretty much describes my career:
“Managers: How do You Manage a Cat?”