condition mean min max ZT0-3 2.8342733333333334 2.8342733333333334 2.8342733333333334 ZT4-7 3.135465 3.135465 3.135465 ZT8-11 1.1489850000000001 1.1489850000000001 1.1489850000000001 ZT12-15 1.1717235000000001 1.1717235000000001 1.1717235000000001 ZT16-19 1.88165 1.88165 1.88165 ZT20-23 1.98645 1.98645 1.98645