How can i calculate the average of a custom event value on GA4?

i have login time for multiple users and i want to show the average, min and max of the login time. how can i do that on GA4 ? following is my code:

gtag('event', 'login_time', {
    event_category: 'timing',
    event_label: 'Time to login',
    value: Math.round(timeToLogin) // Time in milliseconds
  })

i am able to get the login time on GA4 but it shows me the sum of all values. how can i get the average instead