In Canada, my home and native land, education is a provincial matter. In order to 'pass' a course, the minimum grade is 50%. If you managed to get an 80% (=A) average, you would be considered an honors student, and you could gain admission as an arts or science student at most Canadian universities.

In the United States of America, where everything is "bigger and better", education is a federal matter. In order to 'pass' a course, the minimum grade is 70%. If you managed to get an 80% (=C) average in N.C., you would be considered an average student, and you would be lucky if you could gain admission as a liberal arts student at some community colleges in the USA.

For example, at UCLA, for Fall 2006 admission, they received 47,317 applications, of which ~21,000 had GPAs of 4.0 or above in high school. Like the U.S. dollar, where inflation reduces purchasing power, grade inflation reduces the value of a student's high school GPA as a measurement of achievement. Read more about grade inflation here in a USA Today article.