condition mean min max ZT0-3 6.383065 6.383065 6.383065 ZT4-7 4.19921 4.19921 4.19921 ZT8-11 4.509105 4.509105 4.509105 ZT12-15 4.868705 4.868705 4.868705 ZT16-19 8.156025 8.156025 8.156025 ZT20-23 8.675564999999999 8.675564999999999 8.675564999999999