NUMATS just updated 2013 statistics. It is pretty competitive year. Possible cutoff criteria fall in these range:

Grade 3: 76-80 (15 out of 1003)
Grade 4: 84-88 (37 out of 2587)
Grade 5: 92-96 (38 out of 3880)
Grade 6: 97-99! (30 out of 3024)