Dashed line graph for parts of the line

Hello,

I would like to use two line styles for the same graph to denote value above and below a certain threshold: twoway (tsline var if var<=1) (tsline var if var>1, lpattern(dash))

I also tried creating two variables, one for values <=1 and another for values >1. But in both cases I run into the problem that - because the values for each variable to do not occur continuously - I get different shapes than if I were to just draw one line for all values. What I would like is to have the same shape as when I don't split it, but with a dashed line for values above 1.

Could anyone suggest a solution?
Many thanks!