It will vary with age, weight, fitness, pedalling style, the design and fit of the bike and a number of other variables. Assuming you have 700c wheels you're on about 69 gear inches. That's roughly what I ride for general purpose riding, commuting and some easy cross country on a road bike with drops. I'm 57 years old and not as fit as I was, so if you're after speed on the flat as a priority, you can probably increase your ratio a bit from where you are now.