@staticmethod
def inc_stats(result_vec, start_date, idx, invented_on, today, efe):
    """Increment statistics for the given time period"""
    start_index = (invented_on - start_date).days
    end_index = (today - start_date).days
    for i in range(start_index, end_index + 1):
        result_vec[i][idx] += efe
