\begin{table}%t2
\caption{\label{tab:ASM flares}Characteristic level and duty cycle of HBLs considered.}
%\centerline
 {
\begin{tabular}{l|cccccc}
\hline\hline
Source name & 	$R_{\rm char}$ (ASM c/s)	
& $\sigma_{\rm char}$ (ASM c/s)  & $D_{1\sigma}$ (\%) & $S_{1\sigma}$ (\%)
& $D_{3\sigma}$ (\%) & $S_{3\sigma}$ (\%) \\
\hline
Mkn~421  &    0.5 & 0.4 & 40.3   &   1.0 & 18.1  & 0.5 \\
Mkn~501  &    0.4 & 0.2 & 25.8  & 3.0 & 9.7  & 2.3 \\
1ES~1959+650  &	0.3 & 0.2 & 14.2  & 7.1 & 2.6  & 9.5\\
1ES~2155-304  & 0.2 & 0.4 & 27.0  & 22.1 & 4.9  & 18.8\\
%1ES2005-489 &   5.5563354 & & &0.071\\
\hline
\end{tabular}}
\par
\medskip
For each HBLs considered we give the characteristic level $R_{\rm char}$ and its 
standard deviation $\sigma_{\rm char}$. The duty cycle for active state
$D_{1\sigma}$ and for very high states $D_{3\sigma}$ is also reported together with the 
relative intrinsic fluctuations still present above the $R_{\rm char}+1\sigma$ or $R_{\rm char}+3\sigma$ 
threshold due to RXTE/ASM ($S_{1\sigma}$, $S_{3\sigma}$).
\end{table}