Like a lot of things, "it depends". Type of plastic, use case, source of the recycled plastic, and type of injection molding machine all come into play. In practice, it's probably less than 1/3 of post-consumer plastic by a decent margin just because processing god knows what plastic people put in the bin into something you can injection mold requires massively expensive sorting, cleaning, treating, and re-pelletizing.

An interesting point to consider here is that if oil production ever goes down for whatever reason and virgin plastic prices go up as a result, post-consumer plastic recycling becomes a more attractive business prospect.