condition mean min max ZT0-3 17.092651 17.092651 17.092651 ZT4-7 15.9472875 15.9472875 15.9472875 ZT8-11 15.982185000000001 15.982185000000001 15.982185000000001 ZT12-15 15.623453 15.623453 15.623453 ZT16-19 16.5437235 16.5437235 16.5437235 ZT20-23 19.1681965 19.1681965 19.1681965