Denominator: every recorded way a stay ended. A transferred animal is counted again at the facility that receives it, so transfers inflate the total. Leaving transfers out, 8.8% of cats went home.
Simple difference-in-differences: each council's change, minus the median change for councils with no curfew over the same years.
Bars are 95% intervals from 2,000 resamples of facilities. The shaded band spans the ten estimates; the dotted line is the published statewide figure.