condition mean min max ZT0-3 4.406185 4.406185 4.406185 ZT4-7 3.233575 3.233575 3.233575 ZT8-11 3.8093500000000002 3.8093500000000002 3.8093500000000002 ZT12-15 4.47301 4.47301 4.47301 ZT16-19 5.388505 5.388505 5.388505 ZT20-23 4.217925 4.217925 4.217925