condition mean min max ZT0-3 17.046054 17.046054 17.046054 ZT4-7 15.3379045 15.3379045 15.3379045 ZT8-11 15.961059 15.961059 15.961059 ZT12-15 17.429485999999997 17.429485999999997 17.429485999999997 ZT16-19 16.4856445 16.4856445 16.4856445 ZT20-23 22.0887025 22.0887025 22.0887025