condition mean min max ZT0-3 20.29955 20.27565 20.32345 ZT4-7 19.14855 19.14855 19.14855 ZT8-11 11.9705 11.9705 11.9705 ZT12-15 0 0 0 ZT16-19 20.0596 20.0596 20.0596 ZT20-23 20.562 20.562 20.562