condition mean min max ZT0-3 9.562146666666667 7.68069 11.61625 ZT4-7 8.175505000000001 8.175505000000001 8.175505000000001 ZT8-11 7.952975 7.952975 7.952975 ZT12-15 11.708549999999999 10.527899999999999 12.889199999999999 ZT16-19 10.674299999999999 10.674299999999999 10.674299999999999 ZT20-23 11.16815 11.16815 11.16815