@staticmethod
def _year_start(year_find, start_index, step, df):
    """
        TODO: Add docstring

        """
    year_found = 0
    this_ind = start_index
    while year_found == 0:
        this_year = df.loc[this_ind]['Year']
        if this_year >= year_find:
            year_found = 1
            return_step = this_ind - step
        this_ind = this_ind + step
    return int(return_step)
