If the value will always be inside the parentheses and followed by a comma and series of numbers that end the string, you can use

    my ($value) = $var =~ /\(([0-9]+\.[0-9]+)\),[0-9]+$/;
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Explanation can be obtained vie YAPE::Regex::Explain:

The regular expression:

(?-imsx:\(([0-9]+\.[0-9]+)\),[0-9]+$)

matches as follows:
  
NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  \(                       '('
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
    \.                       '.'
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  \)                       ')'
----------------------------------------------------------------------
  ,                        ','
----------------------------------------------------------------------
  [0-9]+                   any character of: '0' to '9' (1 or more
                           times (matching the most amount possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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Note that your line is not valid, because it contains unescaped double quotes inside themselves.