condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 8.492103499999999 8.492103499999999 8.492103499999999 ZT8-11 9.053072 9.053072 9.053072 ZT12-15 8.0525425 8.0525425 8.0525425 ZT16-19 8.8337045 8.8337045 8.8337045 ZT20-23 7.623114999999999 7.623114999999999 7.623114999999999