public void ClearHistory()
{
int lowestPoint = populationLine.GetPointCount() / 2;
populationLine.RemovePointsBefore(lowestPoint);
populationChart.AddXTranslation(lowestPoint);
populationChart.ResetScale();
populationChart.QueueDraw();
birthRate.RemovePointsBefore(lowestPoint);
deathRate.RemovePointsBefore(lowestPoint);
rateChart.AddXTranslation(lowestPoint);
rateChart.ResetScale();
rateChart.QueueDraw();
}
