Intimacy Frequency

I know every couple is different but what would a normal or average frequency of intimacy be for a one week span? I feel like my spouse and I should be more frequent in our intimacy. However, my drive is so low. We have many children who are very young and I just feel so brain dead after dinner time. In addition to frequency, what are some all natural ways to heighten my drive for intimacy? I want to prioritize it.