@Tsering6 It depends on your market. Rentals at the New Jersey shore are known to have returning guests all the time -- in fact, many guests will book for the next year while they are still in residence this year. My properties are in the mountains of NC, and there is a lot of competition as well as guests who want to try different properties in the same area year after year.
My average for returning guests (20+ years renting) is about 15%. I have more than 250+ days rented per year with 60+ different groups of guests, 8 or 9 of whom are repeat guests.
How to attract repeat guests? Superior service, super clean properties and great amenities. I do not immediately offer discounts, but when a guest contacts me for a repeat visit, I will look at my notes about that guest (cleanliness and behavior) and determine if a discount is warranted.