condition mean min max ZT0-3 17.705225 16.2247 19.18575 ZT4-7 6.801795 6.801795 6.801795 ZT8-11 4.94162 4.94162 4.94162 ZT12-15 0 0 0 ZT16-19 7.102925 7.102925 7.102925 ZT20-23 11.43655 11.43655 11.43655