South Korean companies with weak financial footing saw their balance sheets worsen further this year amid a protracted economic slowdown, with their debt ratio sharply rising and their ability to pay back interest declining, industry data showed on Sunday. According to the data, the top 300 in terms of debt ratio, out of 1,501 listed non-financial firms, had the average debt ratio of 279.2 percent as of end-June this year, rising 35.7 percentage points from a year earlier.