A dpreview forum member compiled a list of Nikon DSLR camera sales figures based on serial number registrations from the website Photosynthesis:
D1________________37,759
D1H______________12,383
D1X______________47,109
D2H______________39,823
D2HS______________7,838
D2X______________66,839
D2XS_____________25,211
D3_______________95,390
D3S______________65,228
D3X______________23,158
D4_______________74,130
D4S______________27,884
D5_______________23,430+
D100____________30,2765
D200____________72,5085
D300____________58,8744
D300S___________31,1167
D500____________110,759+
D700____________536,297
D800____________346,903
D800E____________76,540
D810____________257,217
D810A_____________2,306
D850_____________73,967+
Df________________57,812
D600____________234,630
D610____________614,192
D750____________457,373+
Update – here is another selection (also from dpreview):
DX (total) – 28,557,604
FX (total) – 2,966,457
Z (total) – 73,000
Obviously, the sales numbers reported are not 100% accurate – this is just an estimation based on serial numbers reported by Nikon users.