We have known about expolanets for 30 yeasr atleast. How common do you think systems with planets are?

Would you say from the so far observed star systems that a system with planets has a high % of existing?

What is the most non logical-logical planet/system you think of?
For me it's a young brown dwarf with a amonnia world. Amonnia would be liqued at that temperature a brown dwarf could provide