This chart really shows how few low yield devices they have (again comparably).
http://www.johnstonsarchive.net/nuclear/wrjp159r.html
Only the SS-11 Mod 3 Sego with a max number being 630 (a more common estimate is 250). This is out of a number approaching 10000 ICBM/SLBMs.
My guess is that they did not have the Dial a yield concept we used in our Cruise missiles nor that their infrastructure was optimized for smaller missile warheads. From the chart they seem to like the big boys.
edit
I just noticed the SS-N-20 Mod 1 Sturgeon SLBM does give some 200kt options. I don't think this option was on a prior chart I looked at.
SLBM are harder to target accurately so are usually reserved for city busting, but it is another option.