condition mean min max ZT0-3 8.549337612 7.6778104680000006 9.420864756 ZT4-7 4.87263263775 4.4529098335 5.292355442 ZT8-11 4.23326953375 4.2054399935 4.261099074 ZT12-15 4.9103143639999995 3.8977447905 5.9228839375 ZT16-19 12.197005791750001 8.0149591635 16.37905242 ZT20-23 30.2180339575 28.433507435000003 32.00256048