How do I transform this table into a time series?

[rdanutalexandru]

how to convert this:

Year JAN FEB MARCH …

1910 1 2 3

1911 4 5 6

to this:

01/1910 1

02/1910 2

03/1910 3

Thank you!

[Lupp]

You may do it as demonstrated in the attached example. There are many variants.