You could say well see, 20 years ago, 1945, if I were to extend that line backwards, it looks like there were about 52% of the population was smoking. This seems like we're about 52% right over here. Another way to think about it would be to actually try to calculate the rate of decline. And let's say we do it over every 20 years because that'll be useful because we're going 20 years back. So if we go 20 years from this point, so this is 1965, you go 20 years in the future. So that is 10 years and then that is 20 years. So my change in the horizontal is 20 years.