condition mean min max ZT0-3 214.693595 214.693595 214.693595 ZT4-7 323.7668705 323.7668705 323.7668705 ZT8-11 458.121188 458.121188 458.121188 ZT12-15 500.89059399999996 500.89059399999996 500.89059399999996 ZT16-19 748.388063 748.388063 748.388063 ZT20-23 566.0647495000001 566.0647495000001 566.0647495000001