Last I checked the US was sequencing about 1% of patients. In the Houston Methodist hospital system, they sequenced the viral genomes of 56% of patients, which they estimate is about 4% of Covid cases in the Houston metropolitan area: https://www.sciencedirect.com/science/article/pii/S000294402...

Of course, there is a sampling bias there for variants that result in hospitalizations.

Variant-specific proportions can be found here: https://covid.cdc.gov/covid-data-tracker/?ACSTrackingID=USCD...