create stacked bar chart

It's not clear to me exactly what you want. The first thing I notice is that this data is not arranged in a good way for creating a stacked bar/column chart, though it is well arranged as a database for pivot tables and other things. My first guess at what you want:

1) I select the table and insert a pivot chart with year as the row label, diagn1 as the column labels, and sum of count_dx as the pivot values.
2) Select the pivot table and insert a stacked column/bar chart.

I'm not sure exactly what you are looking for, but one of the first steps to creating your chart is rearranging the data in the spreadsheet. As a first guess, a pivot table is a quick and easy way to rearrange and summarize data in preparation for creating charts.

If you are unfamiliar with pivot tables in Excel: https://www.excel-easy.com/data-****...ot-tables.html

In the tutorial's picture of the PivotTable Fields dialog, count_dx would go in the lower right "Values" field.