It probably decreased to 2% because more work as added to the pipeline (doesn't necessarily mean more work beyond those 19026 batches). I think...

Downloaded one of batch 7253 right at noon of 19026 makes it 38.1% of known [purely linear, when above 12013 the batches are 1/10th the size]. On a 2 year timely, 2% what it shows now [this morning still 1%, dango saw that too yesterday, after having fast-tracked towards 20%] is now exactly [very coincidentally] matching the WCGPI number. Guess the Research page only shows the integer part, so 2.9999% would still show as 2%... it would have to as else 99.5% would print as 100% on the timeline, but then we've seen that too whilst work was still flowing ;O].

BTW, seem to recollect that the term 'loaded' was used, so we could be at 100% whilst there's weeks of work right before the feeder/transitioner gauge. :) (Reminds me of the Julie Christie/Donald Sutherland movie... 'Don't look now')

KliK, I suggest, you don't(!!) go with this kind of device because the specs say:

***
Supplied Charging Current

Standard Mode:
All seven USB ports- 0.5 A per port 2
Fast-Charge Mode:
5 standard USB ports- 0.5 A per port 2
2 USB fast charging ports - 1.2 A per port 2
***

This is not going to to be enough to keep more than two 4core Android device on fire (on the mentioned 1.2amp ports!). Of course, if you have old dual-core androids, this might be Ok... but I guess that's not going to be your purpose. Trust me Klik, you want to be going with something like this: Amazon.de -> B015HCLIZ6. Because this device offers 10x 2.4amp it have enough power to go with any common octo-core.
Sadly it does not offer USB-Data... so you'll need to work with wifi... which does quite well for me.
I ended up ordering this device: Amazon.UK -> B00MQZGOM0
The huge AC-DC converter does at the very most barely even get lukewarm, so this is to be recommended. (beware of the power plug edition according to your country)

Any under-powered USB-hub will likely either not going to have all your Androids run at 100% or the converter might get really hot and die soon. (avoid fire hazard, get "serious stuff")

As for your question about it being worth the invest... I'd say "yes". Because even if WCG at some point might not have any Android subproject going on (let's say, Zika and OET come to an end) there will still be other (whitelisted) projects from other Boinc-Projects to be crunched with/on Android. The real risk will be: How long will there be project support for the Android version that you will have installed... for now I would say, Android 4.4.2/.4 still works best. But devices now sell with 5.0/5.1 or 6.0, so if dev's at some point choose to switch to newer Android, you might end up dry.

So far, Android development has been TOO fast for dev's to port crunching to any new Android edition, but with dropping Android 4.2/4.4 sales, I expect this to change at some point. Only future will tell. Do not invest much into your Android devices, if they go "obsolete" the "investment damage" will be limited... (but anyway, still way more efficient than most common x64 units... and way, way cheaper... depending on what you buy and where you buy..... ah yes, and *if* you go with smartphones/tablets, make sure batteries are easily replaceable... batteries die after 1yr of 24/7 connection)

I am disappointed in your quote. That isn't from Spock (originally), but from Sherlock Holmes.