condition mean min max ZT0-3 3.4032400000000003 3.4032400000000003 3.4032400000000003 ZT4-7 2.509365 2.509365 2.509365 ZT8-11 2.90092 2.90092 2.90092 ZT12-15 3.0873299999999997 3.0873299999999997 3.0873299999999997 ZT16-19 4.129875 4.129875 4.129875 ZT20-23 3.92058 3.92058 3.92058