This is the minimum proportion of mobile traffic that this URL will receive, if provided. Therefore, you would just put 30 if you wanted a URL to receive at least 30% mobile traffic. You would input 100 if you only wanted mobile clicks.
Minimum and maximum percentages are upheld click-by-click when distributing clicks.
For instance, Click Handler will balance the T1/non-T1 ratio at 90% if you have a minimum T1 value of 90% and a click occurs. This implies that even if a click were to send the URL, the ratio would not be affected.