如何在R中使用Sweave在xtable标题中包含百分比符号

install.packages("xtable")
install.packages("Hmisc")
library(xtable)
library(Hmisc)

data <- data.frame(A = c(1, 2, 3), B = c(4, 5, 6))
xtab <- xtable(data)

xtab <- add.to.row(xtab, list(NULL, list("Title with % symbol")), 0)

print(xtab, include.rownames=FALSE, include.colnames=FALSE, floating=FALSE, 
      booktabs=TRUE, sanitize.text.function = function(x) x)

\begin{tabular}{rr}
\toprule
Title with \% symbol \\
\midrule
1 & 4 \\
2 & 5 \\
3 & 6 \\
\bottomrule
\end{tabular}