Document uprating parameters

[nikhilwoodruff]

We currently use:

• Population growth by Census: CBO: The Demographic Outlook: 2024 to 2054 (Figure 2)
• CBO's AGI and income by source projections: Revenue Projections, by Category | Congressional Budget Office | Feb 2024
• IRS's total among filer values from IRS SOI Tax Stats - Individual Statistical Tables by Size of Adjusted Gross Income

The part in the codebase that applies the uprating factors is here.

PolicyEngine US code here.

[martinholmer]

@nikhilwoodruff, you assigned fixing issue #54 to yourself on April 23rd. Where do you stand on resolving this issue?