condition mean min max ZT0-3 3.483985 2.175195 4.7064 ZT4-7 1.8458450000000002 1.8458450000000002 1.8458450000000002 ZT8-11 2.66812 2.66812 2.66812 ZT12-15 10.4456175 9.50308 11.388155000000001 ZT16-19 9.581875 9.581875 9.581875 ZT20-23 6.915465 6.915465 6.915465