condition mean min max ZT0-3 1.7191866666666666 1.40111 1.978645 ZT4-7 1.98089 1.98089 1.98089 ZT8-11 1.3931049999999998 1.3931049999999998 1.3931049999999998 ZT12-15 2.79129 2.56947 3.01311 ZT16-19 2.442295 2.442295 2.442295 ZT20-23 2.49015 2.49015 2.49015