condition mean min max ZT0-3 11.921553 11.921553 11.921553 ZT4-7 17.824991 17.824991 17.824991 ZT8-11 13.503336000000001 13.503336000000001 13.503336000000001 ZT12-15 12.7053195 12.7053195 12.7053195 ZT16-19 15.093509000000001 15.093509000000001 15.093509000000001 ZT20-23 16.9384835 16.9384835 16.9384835