Fit fertility rates with a Hadwiger density $$ f(x)= R \frac{H}{T\sqrt{\pi}}\left(\frac{T}{x-D}\right)^{3/2} \exp\left[-H^2\left(\frac{T}{x-D}+\frac{x-D}{T}-2\right)\right],\quad x>D $$ The parameters \(R\), \(D\), \(T\) and \(H\) are chosen to minimize the square of the absolute error in fertility rates.