the cpu percentage will not interpreted as an numeric value

Actually, due to Perl trying to numberify a string in numeric context, it turns out percents written as strings get reasonably interpreted as numbers:

C:\WINDOWS\system32>perl -MDevel::Peek=Dump -le " $a = qq(3.14%); Dump
+ $a; $b = qq(2.718%); Dump $b; print $a <=> $b; Dump $a; Dump $b"
SV = PV(0x1daf58) at 0x44d2660
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x44ebf28 "3.14%"\0
  CUR = 5
  LEN = 10
  COW_REFCNT = 1
SV = PV(0x1dafb8) at 0x44d2300
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x44ebe68 "2.718%"\0
  CUR = 6
  LEN = 10
  COW_REFCNT = 1
1
SV = PVNV(0x1d9288) at 0x44d2660
  REFCNT = 1
  FLAGS = (POK,IsCOW,pNOK,pPOK)
  IV = 0
  NV = 3.14
  PV = 0x44ebf28 "3.14%"\0
  CUR = 5
  LEN = 10
  COW_REFCNT = 1
SV = PVNV(0x1d9268) at 0x44d2300
  REFCNT = 1
  FLAGS = (POK,IsCOW,pIOK,pNOK,pPOK)
  IV = 2
  NV = 2.718
  PV = 0x44ebe68 "2.718%"\0
  CUR = 6
  LEN = 10
  COW_REFCNT = 1
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... They start out as just the string (PV); but after running numeric compare, you can see that it had the right output value for $a <=> $b (1) and afterward, they also have the reasonable floating-point value (NV) of 3.14 and 2.718.