condition mean min max ZT0-3 13.888964 13.888964 13.888964 ZT4-7 13.643545 13.643545 13.643545 ZT8-11 15.2617935 15.2617935 15.2617935 ZT12-15 13.154148500000002 13.154148500000002 13.154148500000002 ZT16-19 12.1459245 12.1459245 12.1459245 ZT20-23 14.233425 14.233425 14.233425