How many title defenses does a champion required to fight in within a year?

If for example, you're a champion, and you have a contract with UFC for a year, would every fight you'd be in be a title defense?|||Title holders in the UFC tend to fight 1-2 times a year. Most of their fights are title fights, but there have been cases where they aren't. Anderson Silva is the current Middleweight champ in the UFC, but he has fought two fights in the Light Heavyweight division while holding the MW belt. Neither of those were title fights.