Thing is, it's going to vary wildly, depending on your writing and WHAT you're writing. The previous books I got a lot of 'Nice writing, but not what we're looking for'. This book was exactly what my agent was looking for* (and ultimately what my publisher was looking for too)
*which is why I subbed to him first, as he'd spoken about wanting exactly this kind of thing.
Very important point! The first novel I submitted to agents I also got lots of praise, even gushing from a few agents, but ultimately it wasn't exactly what they were looking for. I research and triple check that I'm following every guideline for submissions. If they want me to do a rain dance under a full moon I do it. The guidelines are usually still just vague genres and a lot of different ideas can go under those headings.
I don't like posts where people say "You should not be getting a lot of rejections because that means you suck or your works sucks or you don't know what the hell you're doing." NOT true at all. Some people have had 200 rejections and ended up publishing stacks of novels later. There is a lot that goes into a rejection even if your writing is great.
I had an agent who was ready to sign me, but she had just signed someone whose work was similar enough to mine that we would be competing for the same publishers. So she invited me to submit my next novel and she is taking a look at it now.
You just have to keep going. If you have done everything right, you can still rack up the rejections. That doesn't mean you suck and should give up writing.