|Tut tut Carl, that's consistency not accuracy.
Consistency (or dispersion if you're a pessimist) is the spread of rounds about their mpi. Accuracy is the mpi of the rounds in relation to their aimpoint. You can say target but then you have to include target location error.
Accuracy has improved significantly in the last decade or so, starting with ordering target location to the nearest metre when acquired by precise means. However, the 'internal' improvements are the result of: better computational methods notably the use of the modified point mass model, MV radars on every gun (although only a few armies have this), replacement of manual survey with machines including gyroscopic orientation, and new meteor systems that actually measure all the main variables as they ascend and not just some leaving the rest to estimating methods that were not always reliable.
You'll notice I decline to stick my neck out with numbers!