CogAT norms are not generally accessible to the public. It is likely that his composite score is in the low 140s, though, which would put him in the top 1%. As to interpretation, he did very well on all three domains, though very slightly better in verbal and nonverbal than in quantitative. (I wouldn't consider it a significant difference.)
142 is the 99.6th %ile, on this test, which means that he did better than 996 out of 1000 other children his age would have been expected to do on this task. (In the top 4 out of 1000.)
136 is the 98.8th %ile, which means that he did better than 988 out of 1000 other children his age. (In the top 12 out of 1000, or top 1 out of 100.)