Figure 1.

Figure 2.

Figure 3.

Zipf coefficient estimation
| 1995 | 2004 | 2020 | |||||||
|---|---|---|---|---|---|---|---|---|---|
| OLS | SAR | SEM | OLS | SAR | SEM | OLS | SAR | SEM | |
| Constant | 23.94*** | 24.12*** | 24.03*** | 23.59*** | 23.75*** | 23.67*** | 23.00*** | 23.01*** | 23.03*** |
| Ln(P) | −1.68*** | −1.68*** | −1.69*** | −1.65*** | −1.65*** | −1.66*** | −1.60*** | −1.60*** | −1.60*** |
| Rho | −0.026 | −0.022 | −0.001 | ||||||
| Lambda | 0.18** | 0.17** | 0.16** | ||||||
| N | 380 | 380 | 380 | 380 | 380 | 380 | 380 | 380 | 380 |
| R-Squared | 0.95 | 0.95 | 0.95 | 0.95 | 0.95 | 0.95 | 0.94 | 0.94 | 0.94 |