condition mean min max ZT0-3 3.9120056439999997 3.581485775 4.2425255129999995 ZT4-7 2.826615398 2.2938115075 3.3594192885 ZT8-11 4.15386830575 3.6581192189999996 4.6496173925 ZT12-15 9.4762896115 6.241079073 12.711500149999999 ZT16-19 14.56826992 13.348206585 15.788333255000001 ZT20-23 17.253369992499998 16.142940075 18.363799909999997