There are two types of sciences - one is the modern science like Physics, Chemistry, Astronomy, Medical, Geography etc and the other is the traditional ones based on the wisdom and observational knowledge of our ancestors. The examples of the latter are Astrology, Homeopathy, Accupuncture, Tarrot cards, Horoscope, Planchet, Palmistry, Reincarnation etc.
The latter types are very interesting as they do not have any scientific support but they are in practice by people since ages. Another thing is in different communities and societies they have different notions and manifestations. The predictions based on the latter type are more and less statistical in nature.
So whether one believes in them or not, they are there. Believing them is a totally personal choice.
Now coming to the success percentage of these predictions, as they are statistical in nature, they vary case to case basis.
I have one interesting personal case in this regard that when I was in my high school the priest examined my horoscope and told that next 6-7 years are going to be very tough, risky and challenging and after that everything will be all right.
My parents were worried but being a studious student I forgot it and was busy in my school. During the said 6-7 years I had the best time of my life and I always got good division in all the exams and got scholarships and prizes and many accolades. It was the golden period. I was flying high.
As soon as that 6-7 years time was over I was in a big problem as job position was off fully bad in the country and I had to struggle for even a menial job. The financial position of my parents was not good to support me even after the completion of my education. I struggled for 4-5 years here and there cursing that priest and finally I got a break and then it was back to the normal.
So the so called sciences with statistical nature of predictions are to be taken with a pinch of salt.
Knowledge is power.