condition mean min max ZT0-3 3.11088 3.11088 3.11088 ZT4-7 2.366785 2.366785 2.366785 ZT8-11 2.95464 2.95464 2.95464 ZT12-15 2.72573 2.72573 2.72573 ZT16-19 3.2333999999999996 3.2333999999999996 3.2333999999999996 ZT20-23 3.030195 3.030195 3.030195