Based on the reference text, provide a summary of how the monthly benefit amount for social security is calculated.

The monthly benefit amount for social security is calculated by determining an individual's highest 35 years of "indexed" earnings. The sum of the highest 35 years of "indexed" earnings is divided by 420, which is the number of months in 35 years, to determine an individuals Average Indexed Monthly Earnings, which is referred to as AIME. Once an individuals AIME is determined, the formula to calculate the monthly benefit is as follows:
- 90 percent of the first $996 of AIME, plus
- 32 percent of AIME between $996 and $6,002, plus
- 15 percent of AIME over $6,002