condition mean min max ZT0-3 7.155725 7.155725 7.155725 ZT4-7 6.716625 6.716625 6.716625 ZT8-11 6.928025 6.928025 6.928025 ZT12-15 6.035235 6.035235 6.035235 ZT16-19 7.36175 7.36175 7.36175 ZT20-23 6.541650000000001 6.541650000000001 6.541650000000001