I have the following data:
k <- c(294131, 734127, 817963)
ano <- c(1991, 2000, 2010)
dados <- data.frame(k, ano)
I'm doing it this way:
ggplot(dados,aes(x=ano,y=k)) + geom_point() + geom_line() + scale_x_continuous(limits=c(1991, 2010))
But the graph looks like this: 
I wanted the years 2005 and 1995 not to appear, but 1991.
Andrei,
the parameter limits is used to define the limits, not the points. For what you want you should use the parameter breaks
ggplot(dados, aes(x = ano, y = k)) + geom_point() + geom_line() + scale_x_continuous(breaks = c(1991, 2000, 2010))
Or if you can take the values of x as discrete at startup:
g <- ggplot(dados, aes(x=factor(ano), y = k, group = 1))
g + geom_point() +
geom_line() +
labs(list(x='ano', y='k'))
