gr tw (scatter pgratioregional year, by(region)) (lfit pgratioregional year, by(region)) ///
xlabel(1996(1)2006, angle(45)) xline(2001, style(dashed)) ///
xtitle("", margin(medsmall) size(medlarge)) ///
ytitle("Spending", margin(medsmall) size(medlarge)) scheme(s1mono) ///
legend(off) note ("Note: The vertical dashed line marks 2001.", size(tiny))

By running the above, I got ") required" r(100) error.

Thanks!