condition mean min max ZT0-3 12.944109 12.944109 12.944109 ZT4-7 16.970461 16.970461 16.970461 ZT8-11 20.2026695 20.2026695 20.2026695 ZT12-15 20.127555 20.127555 20.127555 ZT16-19 23.8002975 23.8002975 23.8002975 ZT20-23 22.7588685 22.7588685 22.7588685