condition mean min max ZT0-3 3.363635 3.363635 3.363635 ZT4-7 2.68657 2.68657 2.68657 ZT8-11 2.751695 2.751695 2.751695 ZT12-15 3.1942 3.1942 3.1942 ZT16-19 2.900305 2.900305 2.900305 ZT20-23 2.49121 2.49121 2.49121