condition mean min max ZT0-3 20.738439 20.738439 20.738439 ZT4-7 16.384294 16.384294 16.384294 ZT8-11 16.93457 16.93457 16.93457 ZT12-15 17.311538 17.311538 17.311538 ZT16-19 15.410719 15.410719 15.410719 ZT20-23 15.2222135 15.2222135 15.2222135