how exactly can this ratio be increased? is there a threshold or algorithm that determines your monetized views vs total views?
I don't think it's an algorithm. It has to do with what the advertisers are willing to buy at auction. There are a lot of factors involved. One is the type and subject area of your content. Advertisers want to target certain keywords and subjects. Some topics are going to be more in demand by advertisers than others.
For example, let say you just have a vlog video about having a hard day at work. There is probably not a whole lot of good keywords that an advertiser would what to target. At best, you might attract some ads intended for the public at large. If you did a video about doing a repair to Ford vehicle, then you might see Ford commercials, ads to some local Ford dealerships, and maybe even some automotive tool ads. Stuff like that will increase your ratio.
Your competition will decrease your ratio. An advertiser is generally going to pay YouTube a set amount of money for a given number of views. If you have a lot of competition (i.e. videos covering the same topics or similar demographics) then those ads views are going to get spread pretty thin.
Demographics is also going to make a huge difference. Based on my content, I attract an older crowd. Only 10% is under the age of 24. The majority of them are likely to have money and not be a broke teenager or college student. Advertisers really want that 24-44 age group. My viewers are going to see more of the luxury car ads, more beer and alcohol ads, tax prep ads, etc. More monetized views are going to get sent to my channel instead of a gaming or minecraft channel.
Your location will also play a role. Advertisers only want to target certain countries. If you live outside of the United States, you're going to be at a disadvantage.
There is no easy answer to increasing your monetized views. You could re-target a more lucrative demographics with your channel, but there is going to be a lot more to it.
