During the 1990s the rate fluctuated between 64% and 66%. 

As your rents increase (either from making repairs, or market fluctuations), your value goes up.

What are some factors that could cause these percentages to fluctuate?

The cost for an insurance policy can fluctuate a lot depending on the location of the property.

So if the utilities fluctuate enough you're in the hole.

It pretty much comes down to risk/reward on the prime rate fluctuating.

If you cross major roads you will be in a different subdivision and find big fluctuations. 

We all will look forward to some insights to the fluctuating world of commercial financing.

All of this and many other factors need to be considered running a restaurant.The biggest issue a one off restaurant faces is food quality and pricing.Small places can't order in massive quantities so do not have long term food contracts locked in at a set price like chains do.Instead food cost fluctuations can hurt a small restaurant plus the quality you get from a supplier might be good one week but the next a new company came in to the food supplier and gave them a cheaper deal to use their product and try it out.The new product may be better,the same, or worse.The problem is you pay the same price and charge the customer the same price as before but it might not taste as good.I don't know how you will buy this restaurant as you have no experience as an owner.You can't just open a restaurant and expect people to come in.A few will but not enough to make a great business.You have to pound the ground and press palms and get the product with free samples into people's mouths.This will generate buzz for your restaurant and create customers with a relationship.Customers are habit creatures.Get them a great experience,great food,decent price and you will get repeat business.

*Rentals fluctuate, so be prepared for the best and worst.