condition mean min max ZT0-3 4.461012500000001 4.39484 4.527185 ZT4-7 6.15705 6.15705 6.15705 ZT8-11 7.672585 7.672585 7.672585 ZT12-15 0 0 0 ZT16-19 9.486925 9.486925 9.486925 ZT20-23 11.9118 11.9118 11.9118