Pyth, 36 bytes

s/RC-QTrV"2FUdnx‚Œ– ª¾""Qjyƒ—¡°¿Éâû

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Pyth, 36 bytes

s/RC-QTrV"2FUdnx‚Œ– ª¾""Qjyƒ—¡°¿Éâû

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Explanation

              "...   # String literal with end of ranges minus 10 as characters
         "..."       # String literal with start of ranges minus 10 as characters
       rV            # Generate the ranges
 /R                  # Count occurrences of 
   C-QT              # input minus 10 converted to a characters (based on ascii value)
                     # in each of the ranges
s                    # sum

Pyth, 39 bytes

s/R-QTrVCM"2FUdnx‚Œ– ª¾"CM"Qjyƒ—¡°¿Éâû

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Pyth, 36 bytes

s/RC-QTrV"2FUdnx‚Œ– ª¾""Qjyƒ—¡°¿Éâû

Try it online!