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<p>The scores are designed to reflect comparable skills: a 600 in one year represents the same level of ability as a 600 in another year even though the tests taken were different. On the other hand, a reading score of 600 could be the 80th percentile one year and, say, the 75th percentile the next year but in practice the percentiles don’t change very much (example: 2009 CR score 600 = 79th, 2010 CR score 600 = 80th).</p>