condition mean min max ZT0-3 21.552831 21.552831 21.552831 ZT4-7 16.3290245 16.3290245 16.3290245 ZT8-11 23.2713285 23.2713285 23.2713285 ZT12-15 21.055094 21.055094 21.055094 ZT16-19 25.1596925 25.1596925 25.1596925 ZT20-23 23.278392 23.278392 23.278392