I think that in China who mining the 90% of all bitcoin nowdays, it's make sense cause the best proof is statistics. But i maybe somewhere people saving more coins.
Do you have any proof for this 90% figure? I would agree that China is one of the leaders in Bitcoin mining... but this 90% figure seems to be just exaggeration. It is more likely to be somewhere around 30% or 40%. In other countries also, there are mining farms. China is not the only country with mega mining businesses.
Current mining pools stats indicate that China has some 72% of the "hashrate" which I imagine would correlate very closely with BTC winnings of each miner.
F2Pool: 23%
AntPool: 21%
BTCC Pool: 14%
BW.COM: 11%
HaoBTC: 3%
Total Chinese pools: 72%
https://blockchain.info/poolsOK, I would guess that some Americans (and others) may have their hardware grinding away with some of these, but if I had to guess I would think that the majority (probably by far) of BTC production (by Chinese citizens) would be well over 50% of that 72%. Europe also is mining BTC, so what is left for the USA would be well under 50% of current production.
But as someone above mentioned, a lot of BTC was mined in the years before it caught on big.
So, the USA and China having roughly the same BTC "held" would be about equal.