There are a lot of way for money laundering but bitcoin is the best way among all the way of money laundering and for becoming favorite of bitcoin is one of the main reason is money laundering.
Bitcoin being a place for money laundering makes perfect sense because of anonymous factors. But in my opinion the percentage is not big because right now bitcoin has become a place of speculation for big capital owners because the price is fluctuating, so large investors can enjoy large profits in a short time.
Certainly different from general money laundering places such as banks, gold investment or buying property, of course the price continues to rise even though it is not as fast and as high as biotcoin. If bitcoin becomes a place for money laundering it is certainly very risky, because if the price goes down the money from the crime will decrease in value.
There are many ways to money laundering likes you say about gold or property investment which is physical investment that's the big risky from Bitcoin. Because BTC is anonymous and it's not traceable by government but gold or property is visible. BTC is the best and safest way to money transfer in another countries.