It's ok that others are little off topic here though.

If you want to look up the original article, which has links to sources and to other great resources, (I can't link as per BP rules) the article is called "33 Real Estate Statistics That'll Change Your 2019 Strategy" - by Mike BlankenshipGeneral Real Estate Statistics In 2018, 5.5 million existing homes were sold in the U.S. 

Off topic to your question, but what lender did you use for a cashout refi in Philly?

All, can you recommend any types of movies, where one of the topics are life around the Real estates investing matters on US market?

BP has TONS of good podcasts and articles about what people are concerned about when buying a duplex (have you met current tenants, what do rents go for in the area, is there separate metering for each unit, etc.) 

So I've been thinking about ways to increase the overall income from a few duplexes that I own in NE Ohio and wanted to see if anyone else had ever tried this, after searching the forums I didn't see much on topic, but if anyone has experience, I'd love to hear how it turned out (the good, the bad & the ugly so to speak)...I've noticed over the past two years that there are only two approaches to washer's and dryers, either provide them as part of the rent or only hookups are included.  

Don’t let the articles you read scare you.

I am looking for any good real estate books on the following topics and wanted to know if you guys had any you could personally recommend.

Hi @Vipul Patel,I purchased a duplex in North Hollywood and posted an analysis of my purchase here. https://www.biggerpockets.com/forums/223/topics/575632-closed-my-first-house-hacking-deal-in-los-angeles-la-part-1Hope this helps.

@Kristen Chapin You've loaded a lot of topics into your question.