condition mean min max ZT0-3 7.238888888666667 7.238888888666667 7.238888888666667 ZT4-7 6.640000000000001 6.640000000000001 6.640000000000001 ZT8-11 6.060555555333334 6.060555555333334 6.060555555333334 ZT12-15 5.151111111 5.151111111 5.151111111 ZT16-19 4.332222222333333 4.332222222333333 4.332222222333333 ZT20-23 4.737777778 4.737777778 4.737777778