Good call! They have info on general population which shows about double the number of horses I originally thought (at least in 2016), and declining at a good clip of 10%+/decade)
. So drop is still large but just a bit smaller.
The general point is before cars horses were used a lot, entire industries were based around them and our now gone. The toy factor does not compensate because of cost and inconvenience of owning a horse.