It is difficult to find people in the range 100 to 125. The test has a high internal consistency (alpha of 0.88) so we can make a fair assumption that the test discriminates well in the range where IQ-scores are given. When I compare test-scores from professional tests, I see that the correlation is equally high across the entire scale.
Generally, a score of 100 is considered average in an IQ score range. Over time, a researcher named James Flynn realized that IQ scores were rising. This increase in IQ scores is known as the QiNc.