condition mean min max ZT0-3 3.5253439032499996 2.558204125 4.4924836814999995 ZT4-7 5.9298545165 4.635724411 7.223984622 ZT8-11 8.3905492435 7.756930177 9.02416831 ZT12-15 8.216968714 6.463178708499999 9.970758719500001 ZT16-19 11.893605950249999 10.230772890499999 13.55643901 ZT20-23 12.885907015 12.11036952 13.661444509999999