Workers at Korea’s top 100 companies received on average 6.04 million won ($5,362) per month in the first half of the year, while their CEOs were paid over 12 times more, data showed Monday.

CEOs registered as boardroom directors received on average a monthly paycheck of 73.6 million won between January and June, according to the Korea 20000 Corporate Research Institute, a local market tracker.

Employees of SK Telecom, the nation’s largest mobile carrier, earned the most, at 11.02 million won per month on average, followed by employees of S-Oil who received 11 million won per month.

By industry, employees of the petrochemical sector were the highest paid, with an average salary of 41.3 million won in total for six months. Those who worked in the retail sector were paid the least, with an average wage of 27.6 million won in total for six months.

Meanwhile, three boardroom members of GS Retail were paid the most, as they received an average salary of 2.67 billion won in the same period.

The average paychecks for boardroom members of the retail arm of GS Group also rose, as it included the retirement income paid to its vice chairman Huh Seung-jo.