condition mean min max ZT0-3 8.918703 8.918703 8.918703 ZT4-7 8.4820145 8.4820145 8.4820145 ZT8-11 8.702009499999999 8.702009499999999 8.702009499999999 ZT12-15 9.799058500000001 9.799058500000001 9.799058500000001 ZT16-19 8.933506 8.933506 8.933506 ZT20-23 9.6862005 9.6862005 9.6862005