By what percentage should rent increase per year?

Our lease is up for renewal.

- Our contract ends June 28, as we moved in on that date in 2008.
– The apartment is a beautiful 2-bedroom, 2-bathroom in a nice community in Durham, North Carolina.
– Utilities are not included in the monthly rent.
– Though the complex has many amenities, no new amenities have been added since we have moved in.
– We have had no problems with the apartment nor the management.
– Our apartment is in a complex; it is not a single apartment we have rented from a landlord.

There is a rent increase this year (and all years, I’m sure), and the amount of increase is dependent upon the number of months for which we choose to renew our lease. We can choose anywhere between 3 and 18 months. Renewing for between 10–13 months provides the best immediate deal. However, even though the monthly rate if we renewed for 18 months would be higher, this course of action may be better in the long run because it would be longer before we would be subject to another, even higher rent increase.

In any event, my main question is as it stands:

By what percentage should rent increase per year?

- What is fair to ask of tenants?
– If the increase percentage is higher than this, to what degree can the tenants negotiate?
– Should the amount we are being required to pay as a result of this increase equal or exceed the amount that the apartments are going for with new tenants? For instance, if our apartment was $1500/month, and with renewal, there would be a 5% increase, making our apartment $1575 per month, but the apartments are only going for $1550 for new tenants, is this still fair and acceptable?