condition mean min max ZT0-3 3.350605 3.350605 3.350605 ZT4-7 2.47857 2.47857 2.47857 ZT8-11 5.679565 5.679565 5.679565 ZT12-15 4.096385 4.096385 4.096385 ZT16-19 6.49238 6.49238 6.49238 ZT20-23 4.592135 4.592135 4.592135