group y
1  8.87
1  8.44
1 10.98
1 15.15
1  7.46
1  8.12
1 12.79
1 11.16
1  9.95
1 79.95
2 16.67
2 12.66
2 13.03
2 16.21
2 15.21
2 18.15
2 12.01
2 16.58
2 12.97
2 15.61