Symfony: How to make variable work on every page?

I have a question for my Symfony project.

I have this code which shows the number of rows in a given database table:

// BudgetRepository
public function countBudgets()
{
  $qb = $this->createQueryBuilder('budget');
  return $qb
    ->select('count(budget.id)')
    ->getQuery()
    ->getSingleScalarResult();
}

// BudgetController
public function all(EntityManagerInterface $entityManager)
{
  $repository = $entityManager->getRepository(Budget::class);
  $count = $repository->countBudgets();
  return $this->render("budget/budget.html.twig", ['numberOfBudgets' => $count]);
}

It works, but it only works inside budget/budget.html.twig by usung {{ numberOfBudgets }}.

How can I make it work on every page (specifically I want it to be placed in my file called _sidebar.html.twig? Right now if I place {{ numberOfBudgets }} onto _sidebar.html.twig I get this error message “Variable “numberOfBudgets” does not exist”.

How should I rewrite the code?