condition mean min max ZT0-3 267.347076 267.347076 267.347076 ZT4-7 315.849642 315.849642 315.849642 ZT8-11 240.90205149999997 240.90205149999997 240.90205149999997 ZT12-15 233.04375499999998 233.04375499999998 233.04375499999998 ZT16-19 229.766386 229.766386 229.766386 ZT20-23 158.310935 158.310935 158.310935