condition mean min max ZT0-3 521.245611 521.245611 521.245611 ZT4-7 397.828538 397.828538 397.828538 ZT8-11 381.01894 381.01894 381.01894 ZT12-15 389.001288 389.001288 389.001288 ZT16-19 517.6933745 517.6933745 517.6933745 ZT20-23 594.8903695 594.8903695 594.8903695