One of these?
library(ggplot2)
df <- data.frame(
stringsAsFactors = FALSE,
Airport = c("ORD","SFO","SJC","EWR",
"ORD","SFO","SJC","EWR","ORD","SFO","SJC","EWR"),
Year = c(2011L,2011L,2011L,2011L,
2012L,2012L,2012L,2012L,2013L,2013L,2013L,2013L),
Cost = c(100L,150L,200L,250L,150L,
200L,250L,300L,200L,250L,300L,350L)
)
ggplot(df, aes(Year, Cost, col = Airport)) +
geom_line()
ggplot(df, aes(Year, Cost)) +
geom_line() +
facet_wrap(~Airport)