Repairs and Maintenance Cost per Lot Rule of Thumb

For underwriting purposes, and in the middle of the USA what dollar range should repairs and maintenance run per lot for a park of 100-150 lots and no park owned homes with asphalt roads?

Thanks, Bob

$50/lot/year for ‘new’ parks (say, 1980 to present), and $100/lot/year for older parks. Location does not matter nearly as much as age.