If you want to see how many properties were listed over a specific period of time, you will need to use the Additional Fields (Add/Remove) section at the bottom of the search screen to add the Listing Contract Date field.
Find the field in the Available Fields list and either double click it or click the Add button in the center- it will appear at the bottom of the Selected Fields list. Click Back when you're done:
This will bring you back to the search screen (and the Listing Contract Date field will appear at the very bottom of the search screen). Enter the date range you want.
Now fill out any other criteria you want in your search (town, price, etc.).
*** Suggestion: You may want to leave every option in the Status field blank/unchecked. If you select any status(es) and enter a Listing Contract Date range, your results will be limited to those listings that were entered in the MLS during your specified period that are still in the status(es) you selected. A more comprehensive search would include all listings entered during that period, regardless of their current status. ***