condition mean min max ZT0-3 3.221655 2.143245 3.7679150000000003 ZT4-7 1.859495 1.859495 1.859495 ZT8-11 2.612565 2.612565 2.612565 ZT12-15 6.8680075 6.397325 7.33869 ZT16-19 5.567735000000001 5.567735000000001 5.567735000000001 ZT20-23 6.52757 6.52757 6.52757