This has been my №1 chart since you've posted it first here. We may notice that the lower line corresponds to a 2x price increase per year if we round the price to 50$ at the start of 2013. That is an exponential growth 50x2^t, where t is the number of years since 2014. The remarkable thing is that for 7 years Bitcoin has kept hitting these numbers on the way down after several extra exponential growths related to the halvings. And now Bitcoin is even above the line unlike 2015 and most of 2016. This is a strong sign that the exponential growth will continue at least in the next 2-3 years. We can't be sure if 2021 will have that extra growth, but the longer we stay close to the lower line, the better. Sooner or later Bitcoin will touch and may pass through the upper line for a period.

With that regard, what software/site do you use for that chart? I would like to make my own chart with years up to 2025.  In my opinion the lower line is very close to the real price of bitcoin, since it reflects the increasing demand (new accounts added to exchanges, etc.) vs selling pressure on exchanges. For the latter one can judge from the total exchange ballance, which has decreased from 2.8 mil to 2.4 mil in the last 6 months. We can easily find the line equation for each year so that for each day or month the price point is found. Something like y=(x/3)*1600+6400. For example at the end of August (x=8), the price for the bottom line is y~$10 666. We are over 10% above that, so all is good!