condition mean min max ZT0-3 8.481545 8.481545 8.481545 ZT4-7 8.1723145 8.1723145 8.1723145 ZT8-11 7.8764565 7.8764565 7.8764565 ZT12-15 8.449343500000001 8.449343500000001 8.449343500000001 ZT16-19 7.6660645 7.6660645 7.6660645 ZT20-23 9.161228000000001 9.161228000000001 9.161228000000001