Being interested, I opened up lightroom and looked at the number of images I take with my 35mm at wider than f2. I was suprised to find it was 43.7%.
How do you get that info from LR?
The basic premise behind the Lightroom Catalog is that its a database, and you can search for many different terms and parameters.
1. In the Library menu, first highlight the top directory that has all of your images, it should have a big number after it. Lightroom will then search thru all your images. You can also search a subset.
2. Make sure the Library Filter is displayed at the top of the center panel. (view/filter bar)
3. Click the metadata tag and it will open up four levels of filters. You can set each of them to show the file meta data that interests you.
4. Click on the lens you want to view data for in the third panel and change the fourth panel to display aperture.
At that point, you can see the number of images taken at that date range with all or certain cameras for all or a selected lens at various apertures. This is one of the very powerful Lightroom Features.
Buy a book on Lightroom and read it cover to cover. You may be missing out on some very useful features if you just use trial and error to discover how it works.