condition mean min max ZT0-3 1.4550061666666667 1.1098835 1.889745 ZT4-7 1.755835 1.755835 1.755835 ZT8-11 1.2287949999999999 1.2287949999999999 1.2287949999999999 ZT12-15 1.88809 1.7202 2.05598 ZT16-19 2.48117 2.48117 2.48117 ZT20-23 2.335235 2.335235 2.335235