Sorry, yes, correction: “Georgia, imho, is not a state famous for its fast growing performance art and entertainment industries.”

They probably compare (integral f(t)dt - f(t0)* (t1-t0)) - i.e. area under growth curve minus constant demand f(t0) over t1-t0.

These strange outliers probably “just” mean that both South Dakota and Georgia had close to ~zero demand in these sectors at the start period=t0.