condition mean min max ZT0-3 2.7330475 2.636045 2.83005 ZT4-7 4.350395 4.350395 4.350395 ZT8-11 3.4629000000000003 3.4629000000000003 3.4629000000000003 ZT12-15 0 0 0 ZT16-19 7.026445 7.026445 7.026445 ZT20-23 7.293245 7.293245 7.293245