The complete Spring 2011 norms for the CTP4 (which I believe is still the current version) can be found here. The norms may be slightly different, as they use rolling three-year norms (so 2016 norms would be based on 2013-2015 administration years). Your child may or may not have been scored using the spring norms, and he may or may not have been administered the grade 3 test. I expect you should be looking at the independent school norms. It should still give you a decent idea, though.
https://www.erblearn.org/uploads/media_items/ctp-spring-norms-final.original.pdfNote that the tables suggest that your child scores about one standard deviation above the mean for spring of third grade, which would put him around the 85th %ile, on the independent school norms. On the national norms (which are a better comparison to the WIAT-III results; p.91, in case you're wondering), he scores in the beginning of the 99th %ile in mathematics, which is quite comparable to his word reading and reading comprehension scores.
