The four-firm concentration ratios for industries X and Y are 89 percent and 62 percent, respectively, while the corresponding Herfindahl-Hirschman indexes are 2,600 and 1,200. The Dansby-Willig performance index for industry X is 0.6, while that for industry Y is 0.8. Based on this information, which would lead to the greatest increase in social welfare: A slight increase in industry X's output, or a slight increase in industry Y's output?