Fifty employees of Glow Corp. quit the company in 2015. 35 of them quit on their own, while the rest were asked to leave by the company due to poor performance on the job and high absenteeism. The total number of employees in the corporation was 270 in January, 2015. The mid-year employee count was 250, and the number became 220 at the end of the year. The turnover rate at Glow Corp. in 2015 was _____.