condition mean min max ZT0-3 2.2356215 0.8936895 2.951085 ZT4-7 1.135535 1.135535 1.135535 ZT8-11 2.2043600000000003 2.2043600000000003 2.2043600000000003 ZT12-15 2.610355 2.5302550000000004 2.690455 ZT16-19 3.88976 3.88976 3.88976 ZT20-23 3.99193 3.99193 3.99193