I would use something different from a line to indicate number of stores. A darker color or a fatter bar. Or a second bar below the first (growing in the opposite way). Your conclusion seems OK, but why are there a couple of small companies in the expensive range? What other variable drives that? Are these only in big cities? Do they advertise more than others? Does being foreign owned make a difference? This is where data science can go thru a huge number of variables and find the most influential ones. And the for the rest of your research paper (haha) does the pattern hold true in other countries? What about time—does the relation change when costs are high/low, stable/changing? You could write a master’s degree dissertation on this. Also would look good in an interview.