Zener dynamic resistance Rz: Is this graph or the values for Rz correct?
The misleading occurrence in the diagram of the Zener diode characteristic you are looking is that the the anode current axis in the diagram itself is probably graduated in milliamperes (\$\mathrm{mA}\$) while the Anode voltage axis is graduated in volts (\$\mathrm{V}\$). When you work in the breakdown region, beyond \$V_A\simeq V_Z\$, a variation of \$0.1\mathrm{V}\$ for a Zener diode with \$R_Z\simeq 1\Omega\$ causes a variation in anode current of nearly \$100\mathrm{mA}\$, probably out of sight since out of the ranges of diagram. The same thing happens even if the scale is logarithmic.