condition mean min max ZT0-3 6.617615 6.617615 6.617615 ZT4-7 3.6285100000000003 3.6285100000000003 3.6285100000000003 ZT8-11 3.98745 3.98745 3.98745 ZT12-15 6.59047 6.59047 6.59047 ZT16-19 8.710435 8.710435 8.710435 ZT20-23 8.158355 8.158355 8.158355