Take the score for 45-50 candidates: 54. If we assume an even split over the range we have 10.8 candidates for each score between 45 and 50. Subtract 10.8 from 54=43.2. This suggests that 43.2 candidates within the 54 candidates score 49. Add to this the number of candidates scoring 0-45=(210+43)+43=296 as an estimate, 296/492=60.2% approx.