condition mean min max ZT0-3 19.280918 19.280918 19.280918 ZT4-7 18.081629 18.081629 18.081629 ZT8-11 21.8938575 21.8938575 21.8938575 ZT12-15 19.517186 19.517186 19.517186 ZT16-19 21.760742999999998 21.760742999999998 21.760742999999998 ZT20-23 20.7392735 20.7392735 20.7392735