why is there to many homeless animals

1 out of 10 dogs will find a permanent home. There are over 2.7 million homeless animals. I feel like the reason for there being to many homeless animal. Is because a lot of people just leave them in the streets. Or they run away or people give them up. There's still so man homeless animals. And once again 2.7 million is a lot of animal. And no this is not only eats or dogs. This is both of them combine. And most of these animals are found on the streets. And of course if the animal recuse people find them. They help them and also help them find a home that hopes to end up being there forever home.