Till now 738567 blocks have been mined. These blocks have been mined in 4894 days, 18 hours, 40 minutes.
The overall average block time has been 9 minutes and 33 seconds.
This is comparable to the jumps the price has made, we've seen it going 10000x time up but that doesn't mean we're going to see that happening again, same with the hashrate growing, when ASICs hit the market, from 2013 till late 2014 the average was well below 9 minutes, with a lot of periods ending with even 6 minutes and a half on average.
That won't be possible anymore unless you also have a large shutdown before some are getting plugged in again, to keep a 5% increase each period you will need right now about 100k asics, and each time this requirement will grow exponentially.
As o_e_l_e_o mentioned, break it down to 100k or yearly batches and you're going to see that the deviation is going down