You're in luck!
Here is how to use some #rstats functions that calculate party positions & salience from @manifesto_proj data & aggregate these into gov. positions & over time @ParlGov bit.ly/2DMPLuh
Then, it's a breeze.
You can aggregate these per government, per month, and per year.
You want something else: let me know or fork the project on GitHub github.com/demetriodor/go…
and if you notice any mistakes or you want to streamline or extend the code, let me know or go directly to the GitHub repository linked above