condition mean min max ZT0-3 3.821955 3.821955 3.821955 ZT4-7 4.982575000000001 4.982575000000001 4.982575000000001 ZT8-11 1.99277 1.99277 1.99277 ZT12-15 2.5435499999999998 2.5435499999999998 2.5435499999999998 ZT16-19 2.68886 2.68886 2.68886 ZT20-23 3.372555 3.372555 3.372555