condition mean min max ZT0-3 18.112676 18.112676 18.112676 ZT4-7 15.2648505 15.2648505 15.2648505 ZT8-11 15.1173565 15.1173565 15.1173565 ZT12-15 15.112534499999999 15.112534499999999 15.112534499999999 ZT16-19 15.4242595 15.4242595 15.4242595 ZT20-23 14.4349415 14.4349415 14.4349415