condition mean min max ZT0-3 1580.870298 1580.870298 1580.870298 ZT4-7 2178.6687515 2178.6687515 2178.6687515 ZT8-11 2172.1339545 2172.1339545 2172.1339545 ZT12-15 2043.693469 2043.693469 2043.693469 ZT16-19 1827.8360954999998 1827.8360954999998 1827.8360954999998 ZT20-23 1818.5419025 1818.5419025 1818.5419025