I was not around in 2015 but from what I have read about the bitcoin market movement in 2015 I can say it likely following the same pattern in 2019 and at that since history can not repeat it self twice we may not have the same market result in 2019/as it happen in 2015 bit with similar experience and growth. We are all optimistic that the 2020 bitcoin halving will be the starting point of a significant rise of bitcoin price judging from past experience.
Well, what I learnt about the bitcoin market price movement is that history does repeat itself(correction before another halving) and you're wrong when you said history can not repeat it self twice. Besides, this is what the OP is trying to fish out and this is the reason why I also like the fundamental analysis sometime.