condition mean min max ZT0-3 12.669802 12.669802 12.669802 ZT4-7 16.6200635 16.6200635 16.6200635 ZT8-11 16.363165 16.363165 16.363165 ZT12-15 19.2094615 19.2094615 19.2094615 ZT16-19 20.018102499999998 20.018102499999998 20.018102499999998 ZT20-23 30.3109075 30.3109075 30.3109075