Splinterlands Api/Bot Learning: 1. How to view DEC REWARD POOL?

In the game, the timing of renting cards is more important. And if we rent cards when the dec reward pool was high, we will get greater benefits. So how do we view the DEC reward pool? The official provides an interface to check the number of tokens of users.
And the api is: https://api2.splinterlands.com/players/balances?username=
We only need to enter the account number of the reward pool to view the amount of DEC in the current reward pool.
The account's name of DEC REWARD POOL is $REWARD_POOL
Therefore, visit this website: https://api2.splinterlands.com/players/balances?username=$REWARD_POOL

And we will know the timing of renting cards through the amount of DEC in REWARD POOL