427/600 million barrels. So still plenty left...
https://www.spr.doe.gov/dir/images/img2.jpg
You can use the Wayback Machine at archive.org to look at how it looked like in the past. For example, https://web.archive.org/web/202201/https://www.spr.doe.gov/d...
Note that it is mostly Sour oil that is being moved off the SPR. Because that is the more useful type. So you might consider that 200-250mbbl of Sweet oil in the SPR is less-useful and counting the whole 400+mbbls is like counting apples and oranges together and saying you have X amount of fruit.
Note the gradient, rates and the fact that two thirds full is a return to the state of things in the 80s - it is conceivable that it will be empty next year. Although whether it is likely is a political question.