I had never heard this term before last week. We were watching Junior Bake Off/Great British Baking Show: Junior Edition on Netflix and the host said something about carrier bags. I wondered what the heck he meant, but it appeared to be just plastic bags like you'd get from the grocery or stores. (The thin plastic ones, not what's sold here as a reusable shopping bag.)
To answer the question. Not many at the moment... we had a bunch, but we took them to the recycling bin at the grocery store this week, so we only have a few left.