FWIW, your returns are likely significantly above the 5% mark you're referencing. You haven't factored in the unrealized gain of 500k, which would significantly change your returns. All in all, you've got a cash flow positive real estate asset who's valuation has doubled. Unless you purchased 15 years ago, you're likely looking at returns in the mid twenties.

My advice; learn how to actually put together a DCF model and get some real insight into your returns.

EDIT: I realized that my last statement might come off a bit condescending, but that wasn't my intention. Fundamentally, evaluating Real Estate returns is significantly more complex than other investments, such as holding stocks, ETFs, or Bonds. A Distributed Cash Flow (DCF) model will help you gain some understanding that will likely help you to make better decisions about your existing investment and make a more educated plan for the future (e.g. upcoming maintenance, when to exit at what price). You don't have to build a complex model, but even a simple one can help. There's plenty of resources out there, and you don't need much more than Excel to build one.

Source: formerly employed at a national REIT