def find_reasonable_year_ticks(start_time, end_time):
    """
    Function to find reasonable spacing between years for x-ticks.

    Args:
        start_time: Float for left x-limit in years
        end_time: Float for right x-limit in years
    Returns:
        times: The times for the x ticks
    """

    duration = end_time - start_time
    if duration > 1e3:
        spacing = 1e2
    elif duration > 75.:
        spacing = 25.
    elif duration > 25.:
        spacing = 10.
    elif duration > 15.:
        spacing = 5.
    elif duration > 5.:
        spacing = 2.
    else:
        spacing = 1.
    times = []
    working_time = start_time
    while working_time < end_time:
        times.append(working_time)
        working_time += spacing
    return times