Fig. 4.

(Top) Log-log plot of the annual delay per capita $\delta \tau /P$ vs. $P$ for two different cities: Bakersfield, CA and Sarasota, FL. For the same range of $P$ values, the delay is different, and the slopes are different as well. (Bottom) Plot of the rescaled delay $\delta \tau (t)/\delta \tau (t_1)$ vs. $P(t)/P(t_1)$. The curves correspond to different cities and the fact that they do not collapse indicates the absence of a unique scaling determined by a single exponent.