[R] plot subscript text and percentage symbol in graph label axis

[e-letter]

Readers,

I am unable to plot a label consisting of both subscript text and
percentage (%) symbol:

x<-(1:10)
y<-(200:191)
plot(x~y,ylab=expression(~degree~C),xlab=expression(x[2]~%))
Error: syntax error, unexpected ERROR in
"plot(x~y,ylab=expression(~degree~C),xlab=expression(x~%)"

It seems that % is a special character in R? I have looked in the
introductory manual but can see no reference to reserved characters.

Yours,

rhelpatconference.jabber.org
r251
mandriva2008