Previously, my city's population had a happiness of 100%. After some new building, their happiness dipped to about 90% (because there was no longer enough water or sewage treatment).
After fixing that (and creating more buildings) the happiness has risen to 99%. But, I cannot work out how to get that last 1%.
I have checked:
- fire stations
- police stations
It all seems to be OK. EA answers did not provide any new clues.
Currently, my city is at level 13.