def METHOD_NAME(
    year: int, group: pl.DataFrame, pars: Parameters, index_per_year: float, y_max: float
) -> Parameters:
    """updates the initial values of the model parameters"""
    idx = group.get_column("rc").to_numpy()
    mean_index = idx.mean()
    pars[f"g{year}_center"].set(value=mean_index, min=0.75 * mean_index, max=1.25 * mean_index)
    pars[f"g{year}_sigma"].set(value=index_per_year / 4, min=3, max=100)
    pars[f"g{year}_amplitude"].set(value=5 * y_max, min=10)
    return pars