First, the amount appears to be the total through a bank, where this number would be aggregated over a several (possibly many) individuals.
Second, the amounts reported do not reflect the total funds laundered (illicit funds made to appear legitimate) but the total revenue stream, which would be offset by liabilities. For example, one laundering technique I've read about involves buying real estate and selling it at an inflated price to someone who has the illicit funds. For example, A has illicit cash and wants to transfer it to (apparently) legitimate profits by B. B buys a property for $1m. B sells the property to A1 for $2m. B keeps the $1m difference as profit. A1 later sells the property at a loss, and the cycle is complete. Repeat this a few thousand times, but probably with a smaller % margin. But assuming a 100% margin (and the whole laundering effort being exactly this scheme) that'd be $450B total revenue but $225B actually laundered.
Interesting side effect: This pushes up the cost of housing in an area until the launderers abandon it, at which point demand and purchase volume dries up significantly and valuations sink. Additional profit could be made off this market manipulation.