How does Squealer “prove” to the animals that conditions on Animal Farm have gotten better? What other tactics of his are similar to this?

On Sundays Squealer assures them, by reading statistics from a sheet of paper, that their efforts are increasing production many times over. The animals can do nothing but believe Squealer. They can scarcely remember life before the Rebellion.

Squealer also uses this tactic to amend the Seven Commandments when it suits his purpose.