Obs   y     x1    x2  x3 x4
1    3.6  92.2  0.21  0  81
2    0.8  86.7  0.30  0  26
3    2.5  80.2  0.31  0  52
4    2.9  87.2  0.40  0  64
5    1.4  64.9  0.44  0  40
6    0.9  90.1  0.56  0  22
7    3.2  60.7  0.78  0  80
8    2.7  50.9  1.21  0  60
9    2.2  86.1  0.34  1  30
10   5.9  90.0  0.40  1  90
11   2.4  64.6  0.91  1  40
12   1.9  50.0  1.10  1  22
13   2.0  50.0  1.24  1  50
14   1.9  51.2  1.47  1  37
15   3.1  40.1  2.21  1  61
16   2.6  45.0  2.46  1  39
17   3.4  50.0  2.80  1  53
18   3.6  70.0  0.78  1  61
19   2.9  75.0  0.66  1  50
20   3.3  80.4  0.52  1  74