type xy
x    3.4 5.4 7.5 9.3 12.5
y    12  23  45  32  83 23
type xy
x    1.2 4.5 6.5 6.9
y    4   11  74  62
type xy
x    3.4 5.5 7.8 9.2 10.2 11.8
y    2   3   8   20  18   37