condition mean min max ZT0-3 16.152499 16.152499 16.152499 ZT4-7 16.617728 16.617728 16.617728 ZT8-11 17.688843499999997 17.688843499999997 17.688843499999997 ZT12-15 18.5183705 18.5183705 18.5183705 ZT16-19 17.7808345 17.7808345 17.7808345 ZT20-23 19.3471725 19.3471725 19.3471725