Caesar salad, invented in Mexico by Italian immigrants, is still pleasing palates after 100 years

The Caesar Salad has an intriguing history linked to Italy and Mexico. It was created by Italian immigrant Cesar Cardini in Tijuana, Mexico, on July 4, 1924. Faced with a large crowd, Cardini improvised with available ingredients, resulting in the Caesar Salad. Today, it remains a staple, featured on the menu of about 35% of US restaurants.

What was the reason behind the creation of the Caesar salad?

What percentage of US restaurants currently feature the Caesar salad on their menu?