How many nuclear power plants have gone into meltdown?

Many nuclear power plants through history of nuclear energy utilization for electric power generation; namely:

1. Experimental Breeder Reactor One, Idaho, 1951 (only provided power to its own building)
2. SRE at Santa Susana Field Laboratory, California, 1959
3. Stationary Low-Power Reactor Number One, Idaho, 1961
   
4. SNAP8ER at Santa Susana Field Laboratory, California, 1964
   
5. Fermi Nuclear Generating Station, Michigan, 1966
   
6. Chapelcross nuclear power station, Scotland, 1967
   
7. SNAP8DR at Santa Susana Field Laboratory, California, 1969
   
8. Saint-Laurent Nuclear Power Plant, France, 1969
   
9. A1 plant, Czechoslovakia, 1977
   
10. Three Mile Island, Pennsylvania, 1979
11. Saint-Laurent Nuclear Power Plant, France, 1980
12. Chernobyl, USSR, 1986
13. Fukushima, Japan, 2011

This does not include several Soviet submarines that were nuclear powered and suffered meltdowns.