condition mean min max ZT0-3 8.184881 8.184881 8.184881 ZT4-7 9.104927 9.104927 9.104927 ZT8-11 8.6547075 8.6547075 8.6547075 ZT12-15 9.6807975 9.6807975 9.6807975 ZT16-19 8.8758595 8.8758595 8.8758595 ZT20-23 9.537528 9.537528 9.537528