> Were there 20.3 million arrests of offenders?

I don't know of any data from the US but in Switzerland the Federal Police pre sorts all reports from the NCEMC and around 90% are unusable [1] and cannot be acted upon. The remaining 10% are then forwarded to local authorities. There is no data I know of what the final conviction rate looks like. But from what I have gathered from local news paper these departments are usually short staffed.

I suspect that the situation is similar in the US.

[1]: https://fedpol.report/en/fedpol-in-figures/fight-against-pae...

Edit: Fix typo: persorts to pre sorts.