1. A parking system, comprising: a database comprising: (a) a number of parking spaces in a zone; (b) a ratio, comprising a number of vehicles using a certain parking service from a pre-defined general population, divided by a number of vehicles of said pre-defined general population; and (c) a number of vehicles using said parking service and which are currently parking in said zone; and a calculator configured to calculate from said database an estimation of available parking spaces within said zone; thereby enabling a user to obtain information regarding availability of parking spaces in given locations, compared with other locations.