There are no listings for the numbers 15 through 19 in public internet files.
However, the next official grouping is Paper, which holds numbers 20 through 29.
These can be a little confusing, since different countries have translated them to mean different kinds of paper. This is the official USA designation. If you are not from the United States, you will have to check locally for your countries designations.
The following list is copied from: http://en.wikipedia.org/wiki/Recycling_codes
#20 Cardboard (brown Kraft paper and corrugated)
#21 Magazines, Junk Mail (glossy and usually colorful)
#22 Paper — General (which includes office paper)
#24 Paperboard (which includes newsprint and white and gray cardboard)
That’s all the explanation we get. So, we’ll have to muddle through and let the paper recyclers decide what it all means.