How to make a time phased line chart
 

I need to develop a line chart which includes 2 columns of data. Say for
instance the data looks as follows:
5 6
15 9
20 12
50 25

Columns with the 5 and the 6 are for March.
Columns with the 15 and the 9 are for February.
So as we go up, the month increases.

When I make my graph, the 5 and the 6 are first plotted points, the 15 and
the 9 are the second, etc. In other words, it is plotting March, February,
January, instead of January, February, March.

How can I make the chart plot in a logical time phased manner? That is,
Jan, Feb, Mar, etc?

Thanks.
jzis