condition mean min max ZT0-3 6.553825 6.553825 6.553825 ZT4-7 4.7432 4.7432 4.7432 ZT8-11 8.371955 8.371955 8.371955 ZT12-15 11.67935 11.67935 11.67935 ZT16-19 12.62885 12.62885 12.62885 ZT20-23 8.265905 8.265905 8.265905