We need politics out of here. Maybe make the line between HN and the rest of news a bit more clear.
'Stable' here means stable over time. The proportion of political stories goes through pretty big fluctuations (mostly in response to macro social events, e.g. elections), but HN's principles remain the same, and the swings eventually subside*.
If you (or anyone) want to read about what those principles are, I've posted about that many times. Here's one pointer into those explanations: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...
* perhaps ironically, this 'stability' includes the phenomenon of users complaining that HN is turning too much into a political site. For a glimpse into how far back that goes, see https://news.ycombinator.com/item?id=17014869.