condition mean min max ZT0-3 6.699287 6.699287 6.699287 ZT4-7 7.499136999999999 7.499136999999999 7.499136999999999 ZT8-11 7.2702124999999995 7.2702124999999995 7.2702124999999995 ZT12-15 8.192863 8.192863 8.192863 ZT16-19 7.46387 7.46387 7.46387 ZT20-23 7.9120855 7.9120855 7.9120855