The first country to using internet voting as the means for conducting a national election was Estonia. During their 2005 elections, citizens were allowed to vote online for municipal offices. The system was built on an existing national ID framework where citizens had their personal information recorded along with their signatures. These ID cards allowed the election officials to securely certify the votes cast by each individual during the election period.
Estonia’s elections were unique not only in their being the first online election, but that the online polls were open for 7 days. Voters could securely log-on and vote or change their vote during this time, and the votes standing at the time the ballot closed would be counted. Not only does this allow individuals to change their mind, but gives every citizen a greater window of time to participate in the election. During this same period of time, voters could show up at physical polls and cast their ballot. If they chose to vote at a public polling place, their online vote was cancelled and their paper vote would be counted.
After successful municipal elections in 2005, Estonia implemented their online voting program in their national elections in 2007. During the first national election where voters were afforded the ability to vote online, 30,000 Estonians participated via Internet. This means only one in 30 Estonian voters chose to use the online ballot. Two years later in 2009, 104,415 voters participated online. This equates to just under 10% of the total eligible voters. During the most recent 2011 Parliamentary elections, over 140,000 voters participated online. This voting block represents 15% of eligible voters and 24% of voters participating in the election.
The rate of growth suggests that voters have a propensity to use the technology they are most familiar with initially. They can migrate to online options once they are presented, although it's unlikely that they will all move at once.