condition mean min max ZT0-3 8.748069 8.748069 8.748069 ZT4-7 9.0004045 9.0004045 9.0004045 ZT8-11 9.7776395 9.7776395 9.7776395 ZT12-15 8.150327 8.150327 8.150327 ZT16-19 8.421223 8.421223 8.421223 ZT20-23 8.708565 8.708565 8.708565