condition mean min max ZT0-3 13.8087 13.8087 13.8087 ZT4-7 6.858665 6.858665 6.858665 ZT8-11 9.815915 9.815915 9.815915 ZT12-15 12.61375 12.61375 12.61375 ZT16-19 23.2276 23.2276 23.2276 ZT20-23 18.2793 18.2793 18.2793