This varies from person to person, and depending on how long you have been practicing. More important than the amount of time you are distracted is how many seconds it takes you to get back to your focus.
In general, however, do not think much of quantifying the quality of your meditation practice. I know it’s hard, because we always want to know “how well we are doing”, to then either feel proud, or bad about ourselves. This is not helpful, and this is not meditation. Simply follow the practice to the best of your ability. Keep your interest and your effort alive. Practice every day. This is enough for you to reap most of its benefits.
With time your ability to stay with the meditation object, undistracted, increases.