condition mean min max ZT0-3 12.5091 12.5091 12.5091 ZT4-7 7.944965 7.944965 7.944965 ZT8-11 10.45616 10.45616 10.45616 ZT12-15 13.79355 13.79355 13.79355 ZT16-19 19.018050000000002 19.018050000000002 19.018050000000002 ZT20-23 14.1938 14.1938 14.1938