condition mean min max ZT0-3 0.939712 0.3405835 1.5388405 ZT4-7 6.973565 6.973565 6.973565 ZT8-11 14.696100000000001 14.696100000000001 14.696100000000001 ZT12-15 0 0 0 ZT16-19 8.913985 8.913985 8.913985 ZT20-23 6.739035 6.739035 6.739035