condition mean min max ZT0-3 9.142457 9.142457 9.142457 ZT4-7 8.909063 8.909063 8.909063 ZT8-11 8.531921 8.531921 8.531921 ZT12-15 8.774894 8.774894 8.774894 ZT16-19 9.5935505 9.5935505 9.5935505 ZT20-23 7.845233499999999 7.845233499999999 7.845233499999999