condition mean min max ZT0-3 6.587745 6.587745 6.587745 ZT4-7 5.37394 5.37394 5.37394 ZT8-11 5.77885 5.77885 5.77885 ZT12-15 5.73476 5.73476 5.73476 ZT16-19 7.177989999999999 7.177989999999999 7.177989999999999 ZT20-23 6.169165 6.169165 6.169165