Almost every month, I suggest the Subtotal feature to a reader. It's an easy-to-use feature that summarizes data by groups. You define the group and the summarizing function; Excel does the rest ...

Excel Group feature allows users to group rows or columns. Ungroup is used to ungroup a range of cells or data that were previously grouped.

As a result, Excel not only subtotals all data by employee, but it also creates groups and inserts outline levels automatically for your entire data range, as pictured below.

Click the Data tab. Click Subtotal in the Outline group. In Excel 2003, Subtotals is on the Data menu. In the resulting dialog, choose Count from the Function dropdown.

You sorted the data earlier by Category, so you don’t need to sort again. Click anywhere inside the data and click Subtotal (in the Outline group). In Excel 2003, choose Subtotals from the Data ...

On the Data menu choose "PivotTable and PivotChart report". Accept defaults ("Microsoft Office Excel list or database" and "PivotTable") and click Next.