```r
p <- ggplot(data = gapminder, 
            mapping = aes(x = gdpPercap, 
                          y = lifeExp))
p + geom_point(mapping = aes(color = "gray"), size = .01) + 
    geom_smooth(mapping = aes(color = continent),
                method = "gam") + 
    scale_x_log10(labels = scales::dollar)
```