This chart shows that the average high school GPA has increased by 0.32 over the last two decades, from 1990 to 2009. It is based on data from the High School Transcript Study (HSTS) conducted by the National Center for Education Statistics (NCES) at the U.S. Department of Education in 1990, 1994, 1998, 2000, 2005 and 2009.
The increase is probably due to grade inflation. It could also be due to students earning more credits and taking more challenging classes. However, the average high school GPA has increased even as admissions test scores did not, an indication that academic performance has not improved. Note also that the average GPA in core academic courses has consistently remained 0.21 points lower than the overall average high school GPA. That indicates that the higher overall high school GPA is due to grades in non-core subjects.
This next chart is also based on the High School Transcript Study. It shows detail concerning core academic courses. There has been an upward trend in the average GPA among all four subjects. There would be more variation among the core courses if the upward trend were due to improvements in academic performance and not grade inflation.
There have also been increases in average high school GPA when disaggregated by gender, as shown in this chart. Female students have an average high school GPA that is about 0.2 points higher than the average high school GPA for male students.
This chart shows the same data, disaggregated by race. Again, there is a general upward trend in all racial groups.
According to GradeInflation.com, a web site by Stuart Rojstaczer and Chris Healy, the average college GPA has increased by about 0.1 points per decade, from 2.8 in 1983 to 3.1 in 2013. As this graph from the GradeInflation.com web site indicates, the percentage of A’s increased largely due to a decrease in the percentage of B’s and C’s.