condition mean min max ZT0-3 8.388492 8.388492 8.388492 ZT4-7 8.5085065 8.5085065 8.5085065 ZT8-11 8.848725 8.848725 8.848725 ZT12-15 9.1361925 9.1361925 9.1361925 ZT16-19 9.3244805 9.3244805 9.3244805 ZT20-23 9.350214000000001 9.350214000000001 9.350214000000001