condition mean min max ZT0-3 2.1337 2.1337 2.1337 ZT4-7 2.011845 2.011845 2.011845 ZT8-11 2.181175 2.181175 2.181175 ZT12-15 2.14798 2.14798 2.14798 ZT16-19 1.3140876666666668 1.3140876666666668 1.3140876666666668 ZT20-23 2.0837700000000003 2.0837700000000003 2.0837700000000003