condition mean min max ZT0-3 8.848617 8.848617 8.848617 ZT4-7 9.368883 9.368883 9.368883 ZT8-11 9.070467 9.070467 9.070467 ZT12-15 9.3268925 9.3268925 9.3268925 ZT16-19 9.810538000000001 9.810538000000001 9.810538000000001 ZT20-23 9.711325500000001 9.711325500000001 9.711325500000001