That is, unless, you have some other data.
Well, I think that the very heading of the table including the word "steam boats" would point to the column labelled "s. boats" to be a more likely candidate for that data than the one marked "st. ships". Furthermore, if multiple sources mention 3000+ steamboat arrivals a year in that period, I would contend that the column headed "s. boats" and showing 3000+ arrivals indeed represents steam boats, if it's rival for that position shows only 300 arrivals.
Begging your pardon, but I think you're being willfully obtuse on this point.