condition mean min max ZT0-3 6.649705 6.323015 6.976395 ZT4-7 7.16245 7.16245 7.16245 ZT8-11 6.8836200000000005 6.8836200000000005 6.8836200000000005 ZT12-15 0 0 0 ZT16-19 6.7836 6.7836 6.7836 ZT20-23 7.195444999999999 7.195444999999999 7.195444999999999