Is it more efficient to store `struct{}` to represent a set or a `bool`?

package sets

import "testing"

func BenchmarkUnitSet(b *testing.B) {
        for i := 0; i < b.N; i++ {
                values := make(map[int]struct{})
                for j := 0; j < 1000; j++ {
                        values[j] = struct{}{}
                }

                for j := 0; j < 1000; j++ {
                        _ = values[j]
                }
        }
}

func BenchmarkBoolSet(b *testing.B) {
        for i := 0; i < b.N; i++ {
                values := make(map[int]bool)
                for j := 0; j < 1000; j++ {
                        values[j] = true
                }

                for j := 0; j < 1000; j++ {
                        _ = values[j]
                }
        }
}

testing: warning: no tests to run
PASS
BenchmarkUnitSet-8         10000            138503 ns/op           47194 B/op         96 allocs/op
BenchmarkBoolSet-8         10000            141235 ns/op           55261 B/op         96 allocs/op
ok      command-line-arguments  2.836s