The pKb value of an aliphatic primary amine is around 4 units. However, aniline's is 9.4. Therefore aniline is more than five orders of magnitud (more than 100.000 times) less basic than for example methylamanie. This is proof that the electron lone-pair of anilines's nitrogen is strongly delocalized towards the aromatic ring, as it is shown by the corresponding resonance forms.