A chart of age over date would show if age is decreasing over time. It's easier to start a company now, and a changing environment e.g. internet changing benef

A chart of age over date would show if age is decreasing over time. It's easier to start a company now, and a changing environment e.g. internet changing benefits the young because there's less to learn and they have less to unlearn. Notwithstanding YC age being much younger than your three lists being explained by giving them time to fail and them having lower opportunity cost, the average age of founding might still be falling.