I've got a time series data table with one function (row) value available for every month and the second for every 3rd month (every quarter), having holes (empty cell values) for every 2nd and 1st months of a quarter.

When I try to make a chart, I can only draw a bar or a point chart, but I want the actual data points to be interconnected with lines visually filling the gaps.

How to achieve this in LibreOffice 3.6?