condition mean min max ZT0-3 5.412355 4.9959 5.942595000000001 ZT4-7 4.98859 4.98859 4.98859 ZT8-11 4.481574999999999 4.481574999999999 4.481574999999999 ZT12-15 6.570845 5.409695 7.7319949999999995 ZT16-19 8.531460000000001 8.531460000000001 8.531460000000001 ZT20-23 8.173375 8.173375 8.173375