Negative 20 years since 1965, you could view as 20 years before 1965, so that would represent 1945 right over there. And one thing that we could do is very roughly just try to extend this negative linear relationship backwards, and they allow us to do that by saying assuming the trend shown in the data has been consistent. So the trend has been consistent. This line represents the trend. So let's just keep going backwards. Keep going backwards at the same rate. So something like that.