condition mean min max ZT0-3 17.396251 17.396251 17.396251 ZT4-7 17.193907 17.193907 17.193907 ZT8-11 18.0406185 18.0406185 18.0406185 ZT12-15 18.1442555 18.1442555 18.1442555 ZT16-19 23.698572499999997 23.698572499999997 23.698572499999997 ZT20-23 21.745474 21.745474 21.745474