condition mean min max ZT0-3 5.352811666666667 3.388875 6.4032 ZT4-7 3.67433 3.67433 3.67433 ZT8-11 5.37172 5.37172 5.37172 ZT12-15 6.3765475 6.344035 6.40906 ZT16-19 6.165525000000001 6.165525000000001 6.165525000000001 ZT20-23 9.2272 9.2272 9.2272