condition mean min max ZT0-3 26.73385907 26.29693665 27.170781490000003 ZT4-7 4.8246771655 3.5453318955 6.1040224355 ZT8-11 6.0642387517500005 4.2233940545 7.905083449000001 ZT12-15 7.6562267007500004 7.134956686 8.1774967155 ZT16-19 7.2530175135 5.8919025540000005 8.614132473 ZT20-23 15.591732472499999 14.140788025 17.042676919999998