pub const ShillerYear = struct {
    /// A single year's market returns from the Shiller CAPE dataset.
    year: u16,
    /// S&P 500 total return including dividends (decimal, e.g. 0.12 = 12%)
    sp500_total_return: f64,
    /// 10-year Treasury bond total return (decimal)
    bond_total_return: f64,
    /// CPI inflation rate (decimal)
    cpi_inflation: f64,
};