condition mean min max ZT0-3 8.265474 8.265474 8.265474 ZT4-7 9.4677065 9.4677065 9.4677065 ZT8-11 8.778929 8.778929 8.778929 ZT12-15 8.5720805 8.5720805 8.5720805 ZT16-19 8.3990485 8.3990485 8.3990485 ZT20-23 8.594055 8.594055 8.594055