It's higher than average/median in the US, but certainly not exceptional. Pretty normal for certain groups of people. There's a huge gap in miles driven between urban and rural area. US average is something like 13-15k miles per year (for all driving, not just commute).

20,000 miles solely for commuting would be about 43 miles each way (if you work 235 days per year), which is obviously more unusual than 20k total miles driven from all sources.