condition mean min max ZT0-3 8.312226 8.312226 8.312226 ZT4-7 8.5059465 8.5059465 8.5059465 ZT8-11 7.944728 7.944728 7.944728 ZT12-15 9.121273 9.121273 9.121273 ZT16-19 9.96646 9.96646 9.96646 ZT20-23 9.891606 9.891606 9.891606