The U.S.'s population is bigger than Frances.
The French postal density is higher at every quantile, but the ratio is strikingly high at the 95th and 90th quantiles where it exceeds 3 to 1. On average the French postal density exceeds the U.S. by a ratio of 2.5 to 1. This is somewhat less than the ratio of population density between France and the U.S. which is 3.6 to 1.10