The statistics of non-degenerate mutations on the secondary structure of SARS-CoV-2 S protein. The unique and non-unique mutations are considered in the calculation. N_U, N_NU, AR_U, and AR_NU represent the number of unique mutations, the number of non-unique mutations, the average rate of unique mutations, and the average rate of non-unique mutations on the secondary structure of S protein, respectively. Here, the secondary structure is mostly extracted from the crystal structure of 7C2L; the missing residues are predicted by RaptorX-Property.

Secondary structure	Length	N U	N NU	ARU	ARNU
Helix	249	516	9535	2.07	38.29
Sheet	276	711	20 422	2.58	73.99
Random coils	748	2100	350 659	2.81	468.80
Whole spike	1273	3327	380 616	2.61	298.99