condition mean min max ZT0-3 2.1638595 2.1638595 2.1638595 ZT4-7 2.1879999999999997 2.1879999999999997 2.1879999999999997 ZT8-11 1.368616 1.368616 1.368616 ZT12-15 1.8791095 1.8791095 1.8791095 ZT16-19 2.6664874999999997 2.6664874999999997 2.6664874999999997 ZT20-23 3.5144450000000003 3.5144450000000003 3.5144450000000003