Every railroad, railway, express, and every parlor, sleeping or dining car company, or other company not a railroad company owning any cars operated for profit on any railroad in the State of New Hampshire shall pay an annual Railroad Tax as of April 1 of each year. The Railroad Tax is on the market value of the property's full and true value as defined in RSA 75:1. The tax is imposed at the average rate of taxation at that time upon other property throughout the State. Railroad "property" applies to both railroad companies (an enterprise, corporation, partnership, etc.) and private rail cars operated for profit on any railroad in the State of New Hampshire.