$P=0\mathrm{.}01$MPa, the table starts at $T=45\mathrm{.}81C$

$P=0\mathrm{.}20$MPa, the table starts at $T=120\mathrm{.}21C$

$P=0\mathrm{.}50$MPa, the table starts at $T=151\mathrm{.}83$@$C,$ and so on$.$

Explain, with the help of a diagram, why the table starts at different temperatures for varying

pressures.