condition mean min max ZT0-3 10.829067 10.829067 10.829067 ZT4-7 9.751935 9.751935 9.751935 ZT8-11 9.18181 9.18181 9.18181 ZT12-15 9.042436 9.042436 9.042436 ZT16-19 8.617729 8.617729 8.617729 ZT20-23 8.517136 8.517136 8.517136