Last year, the DOD IG published a compendium on issues that the IGs office had identified, but had not been closed, i.e. corrected. This year, they have produced an updated compendium. This is something they plan on doing every year going forward.
https://media.defense.gov/2018/Aug/06/2001950876/-1/-1/1/2018%20COMPENDIUM.PDF
Last year there were 1,298 recommendations. DOD closed 421.
This year, there are 1,558 recommendations. It will be intersting to see how many they close this year.
I briefly worked at the DoD IG. As I was leaving, we were just starting to track the resolution to our prior recommendations across all projects. Don't put too much stock in the numbers. There is a wide range of investigations and corresponding recommendations, and there is some judgement in deciding if a recommendation had been implemented.