Two brief plots of protein structures (protein-DNA/RNA/ligand complexes are excluded) determined by either X-ray or NMR. Structures determined by hybrid method are not counted in the two plots. The dataset was obtain from PDB based on its released statistics by May 10th, 2011.
Molecules with sequence length longer than 1200 residues are also excluded. There are 5075 and 2 structures determined by X-ray and NMR methods, respectively in this category.
FYI: I obtained individual numbers from this statistics page at PDB.