condition mean min max ZT0-3 18.112676 18.112676 18.112676 ZT4-7 18.271788 18.271788 18.271788 ZT8-11 18.112676 18.112676 18.112676 ZT12-15 18.878577 18.878577 18.878577 ZT16-19 18.727604499999998 18.727604499999998 18.727604499999998 ZT20-23 16.0837535 16.0837535 16.0837535