The D7200 is about from 3/4 stop to 1/2 stop quieter throughout the range in RAW. JPG might be better because the D7200 has a different rendering processor. The D500 is about the same but much better in JPG because of a great new Expeed 5 processor so the D7500 will also be very good in JPG but little different between the D7000, D7100, D7200.
When comparing signal to noise floor, the best data for actual noise level use Photographers DR which is numerically lower than Engineering DR
You can compare any cameras from major brand on Bill Claff's excellent web site where he collects raw sample and measures the PDR
Photographic Dynamic Range versus ISO Setting
Just select any cameras to overlay the DR chart. SNR of 2db is about the limit of salvageable images
Pay attention to the measurement markers. A solid dot is native analog ISO, and open circle is beyond the analog ISO range, an up triangle means digital scaling, a down triangle means non-defeatable noise reduction is used in RAW, like the D7100 has which means loss of detail at high ISO, and a diamond marker means the camera applies both scaling and non-defeatable noise reduction in the RAW data. Quieter sensors retain more fine detail by not using RAW noise reduction. Generally speaking, cameras that use non-defeatable noise reduction are pretty quiet but mushy lacking detail and color at high ISO. Sony and Canon for example use hard wired noise reduction in the digital domain to be able to compete with Nikon which has always gotten better DR than other brands from the D90 forward. Canon, even in their top pro models were pretty bad at high ISO and several stops worse at any ISO than any Nikon from D90 forward. Nikon blew away the competition with the D3 but resorted to noise reduction at high ISO. The D4 and D5 do not use RAW noise reduction so preserve a lot more detail.
One of the main reasons Nikon has a loyal following is consistently better DR while maintaining unmolested raw data, with a lot more detail in shadows. The D90 used RAW noise reduction at settings above native analog ISO however, so kept up with the D7000 (actually slightly better than the D7000 between 200 and 1000 iso).
There is not that much difference as most people assume between any model in the Nikon line from the D90 to present, maybe 1/2 a stop in between all the Dx or Fx camera in Dx mode. There has been a steady improvement in JPG rendering engines however, with the D500 noticeably better in color fidelity and saturation in low light. In fact the D500(and surely the D7500) are better than my D800 or the D810 for low light color fidelity and noise distraction. The noise is less distracting with the D500 even with the same signal to noise ratio.
So the whole take away is, whatever camera you have now, it is capable of capturing any image you might see on a gallery wall. Poor quality images is NOT due to your camera if it was built in the last 10 years.