condition mean min max ZT0-3 20.439063 20.439063 20.439063 ZT4-7 10.597276 10.597276 10.597276 ZT8-11 9.6437475 9.6437475 9.6437475 ZT12-15 8.927899499999999 8.927899499999999 8.927899499999999 ZT16-19 7.3158185 7.3158185 7.3158185 ZT20-23 8.672258 8.672258 8.672258