The index of bits is an abstraction of audio level, the top (0) denotes silence, the bottom (23) denotes samples located at the highest 6.0206dB, and every lower index denotes the subsequent 6.0206dB.
If you look at the examples I included in the readme file, you can see that in the electronic music album, there are more samples located at the higher bits and they are packed more tightly within a fewer number of bits. On the other hands, the classical album has fewer samples located at the highest bits, and the values spanned more sparsely among more bits. Which means the classical album has a higher requirement of bit-depth than the electronic album.
Your file is somewhere between my two examples, which means the bit-depth requirement is not particularly high.