condition mean min max ZT0-3 9.058581666666667 6.45008 11.0047 ZT4-7 6.219035 6.219035 6.219035 ZT8-11 6.124594999999999 6.124594999999999 6.124594999999999 ZT12-15 8.398295000000001 7.513120000000001 9.28347 ZT16-19 6.575855000000001 6.575855000000001 6.575855000000001 ZT20-23 12.2595 12.2595 12.2595