condition mean min max ZT0-3 8.773734 8.773734 8.773734 ZT4-7 9.0109715 9.0109715 9.0109715 ZT8-11 9.777993500000001 9.777993500000001 9.777993500000001 ZT12-15 8.766182 8.766182 8.766182 ZT16-19 9.5943745 9.5943745 9.5943745 ZT20-23 8.4890605 8.4890605 8.4890605