You want to make a stacked area graph.

Use geom_area() and map a factor to fill (Figure 4-20):

library(gcookbook) # For the data set

ggplot(uspopage, aes(x=Year, y=Thousands, fill=AgeGroup)) + geom_area()

Figure 4-20. Stacked area graph

The sort of data that is plotted with a stacked area chart is often provided in a wide format, but ggplot2() requires data to be in long format. To convert it, see Converting Data from Wide to Long.

In the example here, we used the uspopage data set:

uspopage

 Year AgeGroup Thousands
 1900       <5      9181
 1900     5-14     16966
 1900    15-24     14951
 1900    25-34     12161
 1900    35-44      9273
 1900    45-54      6437
 1900    55-64      4026
 1900      >64      3099
 1901       <5      9336
 1901     5-14     17158
...