Your global figure includes both donations and value of time donated ([2], pg.8)
Your US figure ([1]) doesn't say anything about value of time donated so I'd assume it is not included.
Finally, the metric where Netherlands and Switzerland come out on top in [3] is in size of philanthropic assets vs GDP. This is noteworthy for sure but is a an entirely different thing than amount of yearly donations.
You're totally right about donations + value of time. Thank you for pointing that out. It's hard to tell if these numbers can be compared. Also [4] paints a very different picture (although it's for 2016).
I think that philanthropic assets should correlate to donations, but you're right also here the numbers from this source cannot be compared to the numbers I mentioned before.
Your US figure ([1]) doesn't say anything about value of time donated so I'd assume it is not included.
Finally, the metric where Netherlands and Switzerland come out on top in [3] is in size of philanthropic assets vs GDP. This is noteworthy for sure but is a an entirely different thing than amount of yearly donations.