The graph may speak more to fluctuation of the gold to USD conversion rate, with housing mixed in.

Most investors focus on cash-flow, so for me a rental property deal should look good even if the property value fluctuates a fair bit.

However my HOA dues fluctuates every month and they give us random reason.

Like is flooring typically  $"X" all the time or does it drastically fluctuate?

Maybe you want this because your total cash flows fluctuate a lot and don't want to have keep a lot of cash reserves.

Rentometer simply collects data from user generated input and listings of rental data and surveys they conduct, so some of this data may be greatly fluctuating, because it pulls from landlords who only post on sites like zillow, zumper, etc.

Over time I have also seen the number of financed properties, reserve amount requirements and percentage down payments fluctuate.

Market fluctuations in the stock market take place every day and wild swings are common.

I concur it seems to that the more units the less the market has fluctuated the only flip to that is when sellers are not well versed in that or their agent has never sold multi-fam and they end up trying to sell it at the same rate as SFR properties.

For our area, your vacancy rate is going to fluctuate significantly depending on where the property is located.