condition mean min max ZT0-3 3.368993333333333 2.2542 4.1715599999999995 ZT4-7 1.777325 1.777325 1.777325 ZT8-11 1.942105 1.942105 1.942105 ZT12-15 2.87559 2.2332549999999998 3.517925 ZT16-19 3.770445 3.770445 3.770445 ZT20-23 4.932465 4.932465 4.932465