Table 4. Fractions of A, T, G, and C at the First, Second, and Third Nucleotide Positions of the Codons in Each Primer Set and Supplier, Determined by Deep Sequencing.

		first nucleotide (%)				second nucleotide (%)				third nucleotide (%)
primer set	supplier	A	T	G	C	A	T	G	C	A	T	G	C
NNNa	1	9	42	33	16	8	43	33	16	9	39	37	15
	2	16	38	30	16	17	38	30	15	16	39	31	14
	3	21	28	32	19	28	19	26	27	22	30	27	21
NNBb	1	19	36	26	19	20	36	26	18	0	44	33	23
	2	18	34	30	17	19	33	31	17	0	39	41	20
	3	21	26	29	24	24	24	30	22	0	36	36	28

^aIn NNN, the expected fractions of A, T, G, and C were all 25%.

^bIn NNB, the expected fractions of T, G, and C at the third position were all 33% and the expected fraction of A at the third position was 0%.