condition mean min max ZT0-3 241.709217 241.709217 241.709217 ZT4-7 553.919052 553.919052 553.919052 ZT8-11 489.66969300000005 489.66969300000005 489.66969300000005 ZT12-15 413.7422835 413.7422835 413.7422835 ZT16-19 240.90587800000003 240.90587800000003 240.90587800000003 ZT20-23 189.2705185 189.2705185 189.2705185