condition mean min max ZT0-3 6.99641 6.99641 6.99641 ZT4-7 7.9435355 7.9435355 7.9435355 ZT8-11 7.802497 7.802497 7.802497 ZT12-15 7.617770999999999 7.617770999999999 7.617770999999999 ZT16-19 9.114023 9.114023 9.114023 ZT20-23 8.809234 8.809234 8.809234