The rate given for Cuba in The World Almanac is 7.3. Whether they've doctored the figures, I don't know.
The figures for the other remaining Communist countries are as follows:
China: 27.2
Laos: 91
North Korea: 27.8 (South Korea's is 7.6)
Vietnam: 29.3.
For the former Communist countries, the rate for Russia is 19.8; the rates for the other former Soviet republics range from 12.3 for Estonia to 82.7 for Azerbaijan and 114.8 for Tajikistan.
Some former Communist countries in Eastern Europe have rates similar to the US or to Western Europe (Slovenia at 4.5, Croatia at 7.1, Hungary at 8.8, Poland at 9.2) while others are somewhat higher (Serbia and Montenegro at 17.9, Romania at 18.9, Bosnia and Hercegovina at 23.5, Albania at 38.6)
Some Third World countries which had Marxist regimes for a time which have very high rates today are:
Afghanistan 144.8
Angola 191.7
Ethiopia 98.6
Mozambique 138.6.
Angola may have the worst rate of any country.