condition mean min max ZT0-3 13.509596 13.509596 13.509596 ZT4-7 13.437041 13.437041 13.437041 ZT8-11 14.450464 14.450464 14.450464 ZT12-15 13.096204 13.096204 13.096204 ZT16-19 13.172668 13.172668 13.172668 ZT20-23 12.751484999999999 12.751484999999999 12.751484999999999