to me it look like many people dump after all time high to take their profit, but still some people hold because think it will go higher. But these people that hold start dump and a little bit people continue hold
Ryan could probably give you a better answer than I can, but I'd agree with what your saying. It's a little obvious, each dump since January 2014 has had less volume than the one before it
Its exactly as you are describing it, the volume of each dump is dropping because the are less and less peopling cashing themselves out.
As for bitcoin currently being in accumulation mode, that's feasible just based on the pattern you pointed out with each dump having less volume than the one before it. I think we're at or close to the bottom, I think the distribution has spread out a little since December 2013 so we could see the price start to move sideways for some time, if that starts happening then that is clean cut, clear as day accumulation