In Monopoly, why is the rent for Piccadilly only $22?

In most of the sets of three properties, the third property, being more expensive, has a rental price $2 higher than its neighbours. Piccadilly, however, is the same as the others in the yellow set, despite being more expensive. Once houses are purchased, Piccadilly returns to status quo, yielding more than its neighbours. Is there any reason for this quirk?