condition mean min max ZT0-3 5.898985 4.968505 6.829465 ZT4-7 6.9098 6.9098 6.9098 ZT8-11 7.0185200000000005 7.0185200000000005 7.0185200000000005 ZT12-15 0 0 0 ZT16-19 13.34075 13.34075 13.34075 ZT20-23 11.00451 11.00451 11.00451