condition mean min max ZT0-3 9.096315 9.096315 9.096315 ZT4-7 11.816775 11.816775 11.816775 ZT8-11 9.14259 9.14259 9.14259 ZT12-15 6.70073 6.70073 6.70073 ZT16-19 6.791385 6.791385 6.791385 ZT20-23 7.56258 7.56258 7.56258