condition mean min max ZT0-3 15.484319 15.484319 15.484319 ZT4-7 14.9919075 14.9919075 14.9919075 ZT8-11 15.888414 15.888414 15.888414 ZT12-15 11.927876000000001 11.927876000000001 11.927876000000001 ZT16-19 13.400652999999998 13.400652999999998 13.400652999999998 ZT20-23 13.655192 13.655192 13.655192