condition mean min max ZT0-3 2.227888353 2.214489312 2.241287394 ZT4-7 1.672151915 1.5748831714999998 1.7694206585 ZT8-11 1.7617540565 1.2773957585 2.2461123545 ZT12-15 3.1634398734999998 2.762153482 3.564726265 ZT16-19 3.1151773052499996 2.8409713759999997 3.3893832345 ZT20-23 4.620669467 4.084988784 5.15635015