condition mean min max ZT0-3 8.62585 8.62585 8.62585 ZT4-7 6.76379 6.76379 6.76379 ZT8-11 6.053565 6.053565 6.053565 ZT12-15 7.834945 7.834945 7.834945 ZT16-19 9.060115 9.060115 9.060115 ZT20-23 8.31864 8.31864 8.31864