That said, the rate hasn't gone up if you look at a 30-year timeframe, but it's a worrying trend nonetheless. It's a bit confusing though because I think you'd want to look at this per-capita. The absolute numbers show a 10-year upward trend, and the per-capita numbers are only split out by age group and show that same 10-year upward trend except it hasn't gone up at all for people under 20, which seems surprising.
But I remain confused because the 10-year weight increase is very small, less than 10% or so, so it is not clear to me that increasing vehicle weight is the most important factor. IIHS mentions road design and front-end design, but not weight as key factors.
