condition mean min max ZT0-3 15.540681 15.540681 15.540681 ZT4-7 15.532139 15.532139 15.532139 ZT8-11 10.3844605 10.3844605 10.3844605 ZT12-15 10.519809500000001 10.519809500000001 10.519809500000001 ZT16-19 9.4265395 9.4265395 9.4265395 ZT20-23 8.3365145 8.3365145 8.3365145