The table shows the number of days per week households eat their dinner together. What percent of households eat their dinner together at least once a week? \begin{array}{|c|c|} \hline 7 \ \text{days}&40\%\\\hline 5-6 \ \text{days}&30\%\\\hline 1-4 \ \text{days}&20\%\\\hline 0 \ \text{days}&10\%\\\hline \end{array}