Zero precent. The government does not subsidize repairs to rental property. However, a bonified repair expense is deductible from your taxable rental income.
But what "exactly" are you calling a repair? There is a difference between a repair and a property improvement, and each is reported/claimed in it's own way. For example, a new roof that costs you $10,000 is not a repair by any stretch. It's a property improvement and must be reported as such. Whereas replacing that broken $15 doorknob is a repair, and is reported as such.