title: Whole number in brackets gets coerced into unusual format in kable table in RMarkdown script
body: <p>I have a basic dataframe/tibble shown as:</p>
  
  <pre><code>  Variable                  `Attended Patients` `Programme Average (Weighted Mean/%)`
    &lt;chr&gt;                     &lt;chr&gt;               &lt;chr&gt;                                
  1 Less than 'O' level       17149 (56.7)        (56.9)                               
  2 'O' level                 9419 (31.2)         (31)                                 
  3 'A' level                 2821 (9.3)          (9.3)                                
  4 University/college        680 (2.2)           (2.3)                                
  5 University degree         132 (0.4)           (0.5)                                
  6 Postgraduate/professional 26 (0.1)            (0.1)  
  </code></pre>
  
  <p>Which I want to visualise in an RMarkdown script. Through built-in RStudio viewer, the table looks fine with:</p>
  
  <pre><code>foo %&gt;% knitr::kable() %&gt;%
    kableExtra::kable_styling(c("striped", "condensed"), full_width = T) 
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Ogzh3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ogzh3.png" alt="enter image description here"></a></p>
  
  <p>However when I then want to create the table in an RMarkdown script, the Programme Average value for the "O-level Variable" has its brackets removed and a decimal added to the end, which I can't ascertain why.</p>
  
  <p><a href="https://i.stack.imgur.com/A0zcP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/A0zcP.png" alt="enter image description here"></a></p>
  
  <p>Sample RMarkdown script and table:</p>
  
  <pre><code>---
  title: "Untitled"
  output: html_document
  ---
  
  ```{r test, echo = F}
  library(knitr)
  library(tidyverse)
  library(kableExtra)
  
  foo &lt;- structure(
    list(
      Variable = c(
        "Less than 'O' level", "'O' level", "'A' level", "University/college", "University degree", "Postgraduate/professional"),
      `Attended Patients` = c("17149 (56.7)", "9419 (31.2)", "2821 (9.3)", "680 (2.2)", "132 (0.4)", "26 (0.1)"),
      `Programme Average (Weighted Mean/%)` = c("(56.9)", "(31)", "(9.3)", "(2.3)", "(0.5)", "(0.1)")
    ),
    row.names = c(NA, -6L),
    class = c("tbl_df", "tbl", "data.frame")
  )
  
  foo %&gt;% kable() %&gt;%
    kable_styling(c("striped", "condensed"), full_width = T) 
  ```
  </code></pre>