How to not show all labels on ggplot axis?

Question

I\'m trying to using ggplot2 to plot this: But as you can see on the x axis you can\'t read anything...

So how can I show on the x axis the value every

Answer 1

The other answers have covered the case where your dates are numerical years, but if (as @Gregor notes) your dates are actual Date objects, it's a lot easier:

scale_x_date(name = 'My date axis title', date_breaks = '20 years',
        date_labels = '%Y')

With scale_date, you can control the breaks with intuitive language and the labelling with (hopefully) familiar strptime notation.