Fair enough. Again, I don’t know if it’s 10%—could be more or even less.
The rest, I think, is mostly from antibiotics, and maybe general hygiene.
The history and causation here is nuanced and difficult. E.g., tuberculosis was basically solved by antibiotics—*but*, it was also declining for many decades *before* that. And I’m not sure if anyone really knows why. Hand-washing? Better diet? Less spitting in the streets? (I’m not kidding, there were actually campaigns to get people to spit less, although I’m not sure if they worked.)
Anyway I’m still researching all this.