condition mean min max ZT0-3 20.275877 20.275877 20.275877 ZT4-7 17.375252 17.375252 17.375252 ZT8-11 17.322516 17.322516 17.322516 ZT12-15 17.132259 17.132259 17.132259 ZT16-19 18.1926195 18.1926195 18.1926195 ZT20-23 19.5070445 19.5070445 19.5070445