The discussion of the nature of railroad expenditure may be concluded by a comparison of the net effects of the developments of the last few years; that is to say, of steadily expanding costs of operation and of slowly and tardily rising rates chargeable for service on the one hand, as over against the results obtained by mechanical improvements and increasing economy of operation coupled with growth of tonnage, on the other. The average cost of transportation has greatly increased. This, according to the statistics of the Interstate Commerce Commission, is shown upon the diagram herewith by the middle curve.[62] The average cost of running all trains per mile, which had fallen from 96 cents in 1891 to 91.8 cents in 1895, rose to $1.07 in 1900, and in 1911 increased by more than one-third, to $1.54 per mile. Against this should be set the fact that while the trains thus cost more to haul per mile, their paying load has increased in somewhat smaller proportion. This is shown by the upper curve on the diagram above mentioned. For freight trains the increase has been from $1.65 to $2.89 per mile. Passenger revenues per train mile have increased less rapidly. This follows from the well-known fact that freight rates have been increased, while passenger rates have not changed for the better during this period; and also that economies in concentration of traffic are necessarily confined to the carriage of freight. The immense gain in trainloads has probably been the main element, among these, as already observed. Among other things this diagram also brings out the effect upon revenue of the substantial rate increases after 1900, coupled with the elimination of rebate losses. It will be observed how sharply the upper curve of revenue per train mile slants upward after 1899, by comparison with the lower line denoting cost. The same thing apparently occurs again after the set-back of 1907.