condition mean min max ZT0-3 15.492666666666667 7.8043 20.9082 ZT4-7 8.238215 8.238215 8.238215 ZT8-11 4.479315 4.479315 4.479315 ZT12-15 8.9035475 6.670945 11.13615 ZT16-19 8.82719 8.82719 8.82719 ZT20-23 10.713035 10.713035 10.713035